687687658 has 12 divisors (see below), whose sum is σ = 1199944962. Its totient is φ = 294723240.

The previous prime is 687687631. The next prime is 687687677. The reversal of 687687658 is 856786786.

It can be written as a sum of positive squares in only one way, i.e., 403326889 + 284360769 = 20083^2 + 16863^2 .

It is a junction number, because it is equal to n+sod(n) for n = 687687596 and 687687605.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3508513 + ... + 3508708.

Almost surely, 2^687687658 is an apocalyptic number.

687687658 is a deficient number, since it is larger than the sum of its proper divisors (512257304).

687687658 is a wasteful number, since it uses less digits than its factorization.

687687658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7017237 (or 7017230 counting only the distinct ones).

The product of its digits is 27095040, while the sum is 61.

The square root of 687687658 is about 26223.7994577445. The cubic root of 687687658 is about 882.6673793272.

The spelling of 687687658 in words is "six hundred eighty-seven million, six hundred eighty-seven thousand, six hundred fifty-eight".