681990944 has 24 divisors (see below), whose sum is σ = 1346675148. Its totient is φ = 339978240.

The previous prime is 681990937. The next prime is 681990973. The reversal of 681990944 is 449099186.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 648211600 + 33779344 = 25460^2 + 5812^2 .

It is a super-2 number, since 2×681990944² = 930223295396022272, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 681990892 and 681990901.

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, 20837 + ... + 42404.

Almost surely, 2^681990944 is an apocalyptic number.

It is an amenable number.

681990944 is a deficient number, since it is larger than the sum of its proper divisors (664684204).

681990944 is a wasteful number, since it uses less digits than its factorization.

681990944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63588 (or 63580 counting only the distinct ones).

The product of its (nonzero) digits is 559872, while the sum is 50.

The square root of 681990944 is about 26114.9563277445. The cubic root of 681990944 is about 880.2233179794.

The spelling of 681990944 in words is "six hundred eighty-one million, nine hundred ninety thousand, nine hundred forty-four".