657920640 has 256 divisors, whose sum is σ = 2314730880. Its totient is φ = 157925376.

The previous prime is 657920633. The next prime is 657920671. The reversal of 657920640 is 46029756.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1072974 + ... + 1073586.

Almost surely, 2^657920640 is an apocalyptic number.

657920640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 657920640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1157365440).

657920640 is an abundant number, since it is smaller than the sum of its proper divisors (1656810240).

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

657920640 is a wasteful number, since it uses less digits than its factorization.

657920640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691 (or 679 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 39.

The square root of 657920640 is about 25649.9637426644. The cubic root of 657920640 is about 869.7434571902.

The spelling of 657920640 in words is "six hundred fifty-seven million, nine hundred twenty thousand, six hundred forty".