681644672 has 16 divisors (see below), whose sum is σ = 1357964250. Its totient is φ = 340822272.

The previous prime is 681644671. The next prime is 681644693. The reversal of 681644672 is 276446186.

It can be written as a sum of positive squares in only one way, i.e., 666465856 + 15178816 = 25816^2 + 3896^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is not an unprimeable number, because it can be changed into a prime (681644671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2662547 + ... + 2662802.

Almost surely, 2^681644672 is an apocalyptic number.

It is an amenable number.

681644672 is a deficient number, since it is larger than the sum of its proper divisors (676319578).

681644672 is an equidigital number, since it uses as much as digits as its factorization.

681644672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5325363 (or 5325351 counting only the distinct ones).

The product of its digits is 387072, while the sum is 44.

The square root of 681644672 is about 26108.3257218842. The cubic root of 681644672 is about 880.0743187922.

The spelling of 681644672 in words is "six hundred eighty-one million, six hundred forty-four thousand, six hundred seventy-two".