251565 has 16 divisors (see below), whose sum is σ = 416256. Its totient is φ = 129600.

The previous prime is 251561. The next prime is 251567. The reversal of 251565 is 565152.

It is not a de Polignac number, because 251565 - 2² = 251561 is a prime.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 251565.

It is not an unprimeable number, because it can be changed into a prime (251561) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 195 + ... + 735.

It is an arithmetic number, because the mean of its divisors is an integer number (26016).

2²⁵¹⁵⁶⁵ is an apocalyptic number.

It is an amenable number.

251565 is a deficient number, since it is larger than the sum of its proper divisors (164691).

251565 is a wasteful number, since it uses less digits than its factorization.

251565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 580.

The product of its digits is 1500, while the sum is 24.

The square root of 251565 is about 501.5625584112. The cubic root of 251565 is about 63.1272309116.

The spelling of 251565 in words is "two hundred fifty-one thousand, five hundred sixty-five".