In mathematics, Euler's idoneal numbers (also called suitable numbers or convenient numbers) are the positive integers D such that any integer expressible...

Dedekind number, and the 128th composite number. 168 is the fourth Dedekind number, and one of sixty-five idoneal numbers. It is one less than a square (132)...

the natural number following 272 and preceding 274. 273 is a sphenic number, a truncated triangular pyramid number and an idoneal number. There are 273...

multiple of 1 to 8), sparsely totient number, Harshad number in base 2 through base 10, idoneal number, balanced number, sum of a twin prime (419 + 421)....

D-number. 520 = 23 × 5 × 13. It is: an untouchable number. an idoneal number a palindromic number in base 14 (29214). 521 is: a Lucas prime. A Mersenne...

primes (67 + 71 + 73 + 79 + 83 + 89), pronic number, sparsely totient number, idoneal number A prime number, sum of seven consecutive primes (53 + 59 +...

30 (3330). palindromic in bases 2, 5, and 30. a lucky number. a cake number. an idoneal number. There are 93 different cyclic Gilbreath permutations on...

natural number following 311 and preceding 313. 312 is a semi perfect number, as it is equal to the sum of some or all of its divisors. 312 is a Idoneal number...

octahedral number, noncototient, totient sum of the first 33 integers, refactorable number. 345 = 3 × 5 × 23, sphenic number, idoneal number 346 = 2 ×...

It is also an idoneal number, a pentatope number, a pronic number, and an untouchable number. 210 is also the third 71-gonal number, preceding 418....

11-gonal number. It is also a refactorable number, a Motzkin sum, an idoneal number, a Riordan number and a noncototient. 232 is a telephone number: in a...

divisors (excluding the number itself) 2040 > 840 It is an abundant number and also a superabundant number. It is an idoneal number. It is the least common...

and convenient metric value has been found." Preferred number Preferred metric sizes Idoneal number 1-2-5 series E-series of preferred numbers Milton, Hans...

A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that...

month, the number of pairs of rabbits is equal to the number of mature pairs (that is, the number of pairs in month n – 2) plus the number of pairs alive...

characteristics: 273 (number) is also a sphenic number and an idoneal number 204 (number) is also a square pyramidal number and a nonagonal number Truncated triangular...

In mathematics, a polygonal number is a number that counts dots arranged in the shape of a regular polygon: 2-3 . These are one type of 2-dimensional figurate...

they were previously discovered in the 1730s by Minggatu. The n-th Catalan number can be expressed directly in terms of the central binomial coefficients...

In number theory, a congruent number is a positive integer that is the area of a right triangle with three rational number sides. A more general definition...

triangular number or triangle number counts objects arranged in an equilateral triangle. Triangular numbers are a type of figurate number, other examples...

In number theory, a perfect number is a positive integer that is equal to the sum of its positive proper divisors, that is, divisors excluding the number...

In mathematics, a harshad number (or Niven number) in a given number base is an integer that is divisible by the sum of its digits when written in that...

highly composite number is a positive integer that has more divisors than all smaller positive integers. If d(n) denotes the number of divisors of a positive...

In number theory, a Carmichael number is a composite number ⁠ n {\displaystyle n} ⁠ which in modular arithmetic satisfies the congruence relation: b n...

In number theory, friendly numbers are two or more natural numbers with a common abundancy index, the ratio between the sum of divisors of a number and...

In number theory, a semiperfect number or pseudoperfect number is a natural number n that is equal to the sum of all or some of its proper divisors. A...

In number theory, an n-smooth (or n-friable) number is an integer whose prime factors are all less than or equal to n. For example, a 7-smooth number is...

In number theory, a narcissistic number (also known as a pluperfect digital invariant (PPDI), an Armstrong number (after Michael F. Armstrong) or a plus...

In number theory, a practical number or panarithmic number is a positive integer n {\displaystyle n} such that all smaller positive integers can be represented...

In mathematics, a Riesel number is an odd natural number k for which k × 2 n − 1 {\displaystyle k\times 2^{n}-1} is composite for all natural numbers...