661973988 has 48 divisors (see below), whose sum is σ = 1666486080. Its totient is φ = 203309184.

The previous prime is 661973959. The next prime is 661974023. The reversal of 661973988 is 889379166.

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, 87958 + ... + 95186.

It is an arithmetic number, because the mean of its divisors is an integer number (34718460).

Almost surely, 2^661973988 is an apocalyptic number.

It is an amenable number.

661973988 is an abundant number, since it is smaller than the sum of its proper divisors (1004512092).

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

661973988 is a wasteful number, since it uses less digits than its factorization.

661973988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7836 (or 7834 counting only the distinct ones).

The product of its digits is 3919104, while the sum is 57.

The square root of 661973988 is about 25728.8551630266. The cubic root of 661973988 is about 871.5259203054.

The spelling of 661973988 in words is "six hundred sixty-one million, nine hundred seventy-three thousand, nine hundred eighty-eight".