687639321640 has 16 divisors (see below), whose sum is σ = 1547188473780. Its totient is φ = 275055728640.

The previous prime is 687639321613. The next prime is 687639321661. The reversal of 687639321640 is 46123936786.

It can be written as a sum of positive squares in 2 ways, for example, as 652938338116 + 34700983524 = 808046^2 + 186282^2 .

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, 8595491481 + ... + 8595491560.

Almost surely, 2^687639321640 is an apocalyptic number.

It is an amenable number.

687639321640 is an abundant number, since it is smaller than the sum of its proper divisors (859549152140).

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

687639321640 is a wasteful number, since it uses less digits than its factorization.

687639321640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17190983052 (or 17190983048 counting only the distinct ones).

The product of its (nonzero) digits is 7838208, while the sum is 55.

The spelling of 687639321640 in words is "six hundred eighty-seven billion, six hundred thirty-nine million, three hundred twenty-one thousand, six hundred forty".