681397664 has 24 divisors (see below), whose sum is σ = 1343597220. Its totient is φ = 340166656.

The previous prime is 681397663. The next prime is 681397727. The reversal of 681397664 is 466793186.

It can be written as a sum of positive squares in 2 ways, for example, as 679123600 + 2274064 = 26060^2 + 1508^2 .

It is not an unprimeable number, because it can be changed into a prime (681397663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4592 + ... + 37200.

Almost surely, 2^681397664 is an apocalyptic number.

It is an amenable number.

681397664 is a deficient number, since it is larger than the sum of its proper divisors (662199556).

681397664 is a wasteful number, since it uses less digits than its factorization.

681397664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33272 (or 33264 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 50.

The square root of 681397664 is about 26103.5948482197. The cubic root of 681397664 is about 879.9680015913.

The spelling of 681397664 in words is "six hundred eighty-one million, three hundred ninety-seven thousand, six hundred sixty-four".