251965 has 16 divisors (see below), whose sum is σ = 361728. Its totient is φ = 164736.

The previous prime is 251947. The next prime is 251969. The reversal of 251965 is 569152.

251965 = 56² + 57² + ... + 97².

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251965 is a prime.

It is a super-2 number, since 2×251965² = 126972722450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 649 + ... + 961.

It is an arithmetic number, because the mean of its divisors is an integer number (22608).

2²⁵¹⁹⁶⁵ is an apocalyptic number.

It is an amenable number.

251965 is a deficient number, since it is larger than the sum of its proper divisors (109763).

251965 is a wasteful number, since it uses less digits than its factorization.

251965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 348.

The product of its digits is 2700, while the sum is 28.

The square root of 251965 is about 501.9611538755. The cubic root of 251965 is about 63.1606716006.

The spelling of 251965 in words is "two hundred fifty-one thousand, nine hundred sixty-five".