657139840 has 64 divisors (see below), whose sum is σ = 1795412160. Its totient is φ = 225303552.

The previous prime is 657139799. The next prime is 657139843. The reversal of 657139840 is 48931756.

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (657139843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68862 + ... + 77821.

It is an arithmetic number, because the mean of its divisors is an integer number (28053315).

Almost surely, 2^657139840 is an apocalyptic number.

It is an amenable number.

657139840 is an abundant number, since it is smaller than the sum of its proper divisors (1138272320).

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

657139840 is a wasteful number, since it uses less digits than its factorization.

657139840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146709 (or 146697 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 43.

The square root of 657139840 is about 25634.7389298194. The cubic root of 657139840 is about 869.3992593895.

The spelling of 657139840 in words is "six hundred fifty-seven million, one hundred thirty-nine thousand, eight hundred forty".