251534661 has 32 divisors (see below), whose sum is σ = 404040960. Its totient is φ = 136141824.

The previous prime is 251534653. The next prime is 251534663. The reversal of 251534661 is 166435152.

It is not a de Polignac number, because 251534661 - 2³ = 251534653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251534663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28381 + ... + 36173.

It is an arithmetic number, because the mean of its divisors is an integer number (12626280).

Almost surely, 2^251534661 is an apocalyptic number.

251534661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

251534661 is a deficient number, since it is larger than the sum of its proper divisors (152506299).

251534661 is a wasteful number, since it uses less digits than its factorization.

251534661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7885.

The product of its digits is 21600, while the sum is 33.

The square root of 251534661 is about 15859.8442930566. The cubic root of 251534661 is about 631.2469307304.

The spelling of 251534661 in words is "two hundred fifty-one million, five hundred thirty-four thousand, six hundred sixty-one".