257720631 has 16 divisors (see below), whose sum is σ = 394368000. Its totient is φ = 146649888.

The previous prime is 257720627. The next prime is 257720633. The reversal of 257720631 is 136027752.

It is not a de Polignac number, because 257720631 - 2² = 257720627 is a prime.

It is a super-2 number, since 2×257720631² = 132839847286076322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 257720592 and 257720601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (257720633) 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, 20656 + ... + 30693.

It is an arithmetic number, because the mean of its divisors is an integer number (24648000).

Almost surely, 2^257720631 is an apocalyptic number.

257720631 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

257720631 is a deficient number, since it is larger than the sum of its proper divisors (136647369).

257720631 is a wasteful number, since it uses less digits than its factorization.

257720631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51598.

The product of its (nonzero) digits is 17640, while the sum is 33.

The square root of 257720631 is about 16053.6796716516. The cubic root of 257720631 is about 636.3798139740.

The spelling of 257720631 in words is "two hundred fifty-seven million, seven hundred twenty thousand, six hundred thirty-one".