257660640 has 72 divisors (see below), whose sum is σ = 879271848. Its totient is φ = 68709120.

The previous prime is 257660639. The next prime is 257660659. The reversal of 257660640 is 46066752.

257660640 is a `hidden beast` number, since 2 + 5 + 7 + 6 + 6 + 0 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 257660595 and 257660604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 88026 + ... + 90905.

It is an arithmetic number, because the mean of its divisors is an integer number (12212109).

Almost surely, 2^257660640 is an apocalyptic number.

257660640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

257660640 is an abundant number, since it is smaller than the sum of its proper divisors (621611208).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

257660640 is a wasteful number, since it uses less digits than its factorization.

257660640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 178952 (or 178941 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The square root of 257660640 is about 16051.8111127686. The cubic root of 257660640 is about 636.3304323059.

The spelling of 257660640 in words is "two hundred fifty-seven million, six hundred sixty thousand, six hundred forty".