640656521900 has 18 divisors (see below), whose sum is σ = 1390224652740. Its totient is φ = 256262608720.

The previous prime is 640656521899. The next prime is 640656521951. The reversal of 640656521900 is 9125656046.

It is a super-2 number, since 2×640656521900² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3203282510 + ... + 3203282709.

It is an arithmetic number, because the mean of its divisors is an integer number (77234702930).

Almost surely, 2^640656521900 is an apocalyptic number.

It is an amenable number.

640656521900 is an abundant number, since it is smaller than the sum of its proper divisors (749568130840).

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

640656521900 is a wasteful number, since it uses less digits than its factorization.

640656521900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6406565233 (or 6406565226 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 44.

The spelling of 640656521900 in words is "six hundred forty billion, six hundred fifty-six million, five hundred twenty-one thousand, nine hundred".