251560161 has 24 divisors (see below), whose sum is σ = 377735904. Its totient is φ = 167300640.

The previous prime is 251560073. The next prime is 251560189. The reversal of 251560161 is 161065152.

It is a happy number.

251560161 is a `hidden beast` number, since 2 + 51 + 5 + 601 + 6 + 1 = 666.

It is not a de Polignac number, because 251560161 - 2¹¹ = 251558113 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (251560961) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 125610 + ... + 127596.

It is an arithmetic number, because the mean of its divisors is an integer number (15738996).

Almost surely, 2^251560161 is an apocalyptic number.

It is an amenable number.

251560161 is a deficient number, since it is larger than the sum of its proper divisors (126175743).

251560161 is an equidigital number, since it uses as much as digits as its factorization.

251560161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2523 (or 2511 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

The square root of 251560161 is about 15860.6481897809. The cubic root of 251560161 is about 631.2682614591.

The spelling of 251560161 in words is "two hundred fifty-one million, five hundred sixty thousand, one hundred sixty-one".