721766656 has 36 divisors (see below), whose sum is σ = 1551545212. Its totient is φ = 333121536.

The previous prime is 721766537. The next prime is 721766693. The reversal of 721766656 is 656667127.

It can be written as a sum of positive squares in 2 ways, for example, as 400640256 + 321126400 = 20016^2 + 17920^2 .

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, 105111 + ... + 111766.

Almost surely, 2^721766656 is an apocalyptic number.

It is an amenable number.

721766656 is an abundant number, since it is smaller than the sum of its proper divisors (829778556).

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

721766656 is a wasteful number, since it uses less digits than its factorization.

721766656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216906 (or 216892 counting only the distinct ones).

The product of its digits is 635040, while the sum is 46.

The square root of 721766656 is about 26865.7152519712. The cubic root of 721766656 is about 897.0134154253.

The spelling of 721766656 in words is "seven hundred twenty-one million, seven hundred sixty-six thousand, six hundred fifty-six".