686637820 has 48 divisors (see below), whose sum is σ = 1665564768. Its totient is φ = 234997760.

The previous prime is 686637779. The next prime is 686637841. The reversal of 686637820 is 28736686.

It is a hoax number, since the sum of its digits (46) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 88057 + ... + 95536.

It is an arithmetic number, because the mean of its divisors is an integer number (34699266).

Almost surely, 2^686637820 is an apocalyptic number.

It is an amenable number.

686637820 is an abundant number, since it is smaller than the sum of its proper divisors (978926948).

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

686637820 is a wasteful number, since it uses less digits than its factorization.

686637820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183630 (or 183628 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 46.

The square root of 686637820 is about 26203.7749188929. The cubic root of 686637820 is about 882.2179845585.

The spelling of 686637820 in words is "six hundred eighty-six million, six hundred thirty-seven thousand, eight hundred twenty".