251112561 has 16 divisors (see below), whose sum is σ = 391547904. Its totient is φ = 140155344.

The previous prime is 251112557. The next prime is 251112581. The reversal of 251112561 is 165211152.

It is not a de Polignac number, because 251112561 - 2² = 251112557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (251112581) 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, 138141 + ... + 139946.

It is an arithmetic number, because the mean of its divisors is an integer number (24471744).

Almost surely, 2^251112561 is an apocalyptic number.

251112561 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

251112561 is a deficient number, since it is larger than the sum of its proper divisors (140435343).

251112561 is a wasteful number, since it uses less digits than its factorization.

251112561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278140.

The product of its digits is 600, while the sum is 24.

The square root of 251112561 is about 15846.5315132366. The cubic root of 251112561 is about 630.8936348066.

It can be divided in two parts, 25111 and 2561, that added together give a palindrome (27672).

The spelling of 251112561 in words is "two hundred fifty-one million, one hundred twelve thousand, five hundred sixty-one".