251901 has 12 divisors (see below), whose sum is σ = 392028. Its totient is φ = 154944.

The previous prime is 251897. The next prime is 251903. The reversal of 251901 is 109152.

251901 = T₁₂₆ + T₁₂₇ + ... + T₁₅₁.

It can be written as a sum of positive squares in 2 ways, for example, as 27225 + 224676 = 165^2 + 474^2 .

It is not a de Polignac number, because 251901 - 2² = 251897 is a prime.

It is a super-2 number, since 2×251901² = 126908227602, which contains 22 as substring.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is an Ulam number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251903) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 960 + ... + 1193.

It is an arithmetic number, because the mean of its divisors is an integer number (32669).

2²⁵¹⁹⁰¹ is an apocalyptic number.

It is an amenable number.

251901 is a deficient number, since it is larger than the sum of its proper divisors (140127).

251901 is a wasteful number, since it uses less digits than its factorization.

251901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2172 (or 2169 counting only the distinct ones).

The product of its (nonzero) digits is 90, while the sum is 18.

The square root of 251901 is about 501.8973998737. The cubic root of 251901 is about 63.1553234699.

The spelling of 251901 in words is "two hundred fifty-one thousand, nine hundred one".