680721556 has 12 divisors (see below), whose sum is σ = 1203544468. Its totient is φ = 336851712.

The previous prime is 680721511. The next prime is 680721557. The reversal of 680721556 is 655127086.

It can be written as a sum of positive squares in 2 ways, for example, as 184144900 + 496576656 = 13570^2 + 22284^2 .

It is a super-2 number, since 2×680721556² = 926763673606122272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (680721557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 876831 + ... + 877606.

Almost surely, 2^680721556 is an apocalyptic number.

It is an amenable number.

680721556 is a deficient number, since it is larger than the sum of its proper divisors (522822912).

680721556 is a wasteful number, since it uses less digits than its factorization.

680721556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1754538 (or 1754536 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 40.

The square root of 680721556 is about 26090.6411573192. The cubic root of 680721556 is about 879.6768596616.

The spelling of 680721556 in words is "six hundred eighty million, seven hundred twenty-one thousand, five hundred fifty-six".