681689664 has 168 divisors, whose sum is σ = 2118299040. Its totient is φ = 208760832.

The previous prime is 681689641. The next prime is 681689677. The reversal of 681689664 is 466986186.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 681689664.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 420247 + ... + 421865.

Almost surely, 2^681689664 is an apocalyptic number.

681689664 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 681689664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1059149520).

681689664 is an abundant number, since it is smaller than the sum of its proper divisors (1436609376).

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

681689664 is a wasteful number, since it uses less digits than its factorization.

681689664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1697 (or 1684 counting only the distinct ones).

The product of its digits is 2985984, while the sum is 54.

The square root of 681689664 is about 26109.1873485178. The cubic root of 681689664 is about 880.0936814867.

The spelling of 681689664 in words is "six hundred eighty-one million, six hundred eighty-nine thousand, six hundred sixty-four".