681558666 has 32 divisors (see below), whose sum is σ = 1386127680. Its totient is φ = 223382016.

The previous prime is 681558659. The next prime is 681558721. The reversal of 681558666 is 666855186.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 87645 + ... + 95103.

It is an arithmetic number, because the mean of its divisors is an integer number (43316490).

Almost surely, 2^681558666 is an apocalyptic number.

681558666 is an abundant number, since it is smaller than the sum of its proper divisors (704569014).

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

681558666 is a wasteful number, since it uses less digits than its factorization.

681558666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7718.

The product of its digits is 2073600, while the sum is 51.

The square root of 681558666 is about 26106.6785708179. The cubic root of 681558666 is about 880.0373029986.

The spelling of 681558666 in words is "six hundred eighty-one million, five hundred fifty-eight thousand, six hundred sixty-six".