681720628 has 24 divisors (see below), whose sum is σ = 1251697664. Its totient is φ = 324453600.

The previous prime is 681720623. The next prime is 681720643. The reversal of 681720628 is 826027186.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681720623) 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 7 ways as a sum of consecutive naturals, for example, 37500 + ... + 52627.

Almost surely, 2^681720628 is an apocalyptic number.

It is an amenable number.

681720628 is a deficient number, since it is larger than the sum of its proper divisors (569977036).

681720628 is a wasteful number, since it uses less digits than its factorization.

681720628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90223 (or 90221 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 40.

The square root of 681720628 is about 26109.7803131317. The cubic root of 681720628 is about 880.1070066157.

The spelling of 681720628 in words is "six hundred eighty-one million, seven hundred twenty thousand, six hundred twenty-eight".