257664640 has 32 divisors (see below), whose sum is σ = 615981060. Its totient is φ = 103065600.

The previous prime is 257664629. The next prime is 257664691. The reversal of 257664640 is 46466752.

257664640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 252682816 + 4981824 = 15896^2 + 2232^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 257664593 and 257664602.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 200661 + ... + 201940.

Almost surely, 2^257664640 is an apocalyptic number.

257664640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

257664640 is an abundant number, since it is smaller than the sum of its proper divisors (358316420).

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

257664640 is an equidigital number, since it uses as much as digits as its factorization.

257664640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 402620 (or 402608 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 40.

The square root of 257664640 is about 16051.9357088172. The cubic root of 257664640 is about 636.3337251494. Note that the first 3 decimals are identical.

The spelling of 257664640 in words is "two hundred fifty-seven million, six hundred sixty-four thousand, six hundred forty".