681440656 has 20 divisors (see below), whose sum is σ = 1421852572. Its totient is φ = 314510976.

The previous prime is 681440633. The next prime is 681440677. The reversal of 681440656 is 656044186.

It is a happy number.

681440656 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 297907600 + 383533056 = 17260^2 + 19584^2 .

It is a super-2 number, since 2×681440656² = 928722735299420672, which contains 22 as substring.

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, 1637871 + ... + 1638286.

Almost surely, 2^681440656 is an apocalyptic number.

It is an amenable number.

681440656 is an abundant number, since it is smaller than the sum of its proper divisors (740411916).

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

681440656 is a wasteful number, since it uses less digits than its factorization.

681440656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3276178 (or 3276172 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 40.

The square root of 681440656 is about 26104.4183233414. The cubic root of 681440656 is about 879.9865080576.

The spelling of 681440656 in words is "six hundred eighty-one million, four hundred forty thousand, six hundred fifty-six".