661965664 has 24 divisors (see below), whose sum is σ = 1335034008. Its totient is φ = 322909440.

The previous prime is 661965659. The next prime is 661965683. The reversal of 661965664 is 466569166.

661965664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 250962 + ... + 253585.

It is an arithmetic number, because the mean of its divisors is an integer number (55626417).

Almost surely, 2^661965664 is an apocalyptic number.

It is an amenable number.

661965664 is an abundant number, since it is smaller than the sum of its proper divisors (673068344).

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

661965664 is a wasteful number, since it uses less digits than its factorization.

661965664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 504598 (or 504590 counting only the distinct ones).

The product of its digits is 1399680, while the sum is 49.

The square root of 661965664 is about 25728.6933986163. The cubic root of 661965664 is about 871.5222672856.

The spelling of 661965664 in words is "six hundred sixty-one million, nine hundred sixty-five thousand, six hundred sixty-four".