661786656 has 24 divisors (see below), whose sum is σ = 1737190224. Its totient is φ = 220595520.

The previous prime is 661786597. The next prime is 661786661. The reversal of 661786656 is 656687166.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (24).

It is a junction number, because it is equal to n+sod(n) for n = 661786599 and 661786608.

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, 3446710 + ... + 3446901.

It is an arithmetic number, because the mean of its divisors is an integer number (72382926).

Almost surely, 2^661786656 is an apocalyptic number.

It is an amenable number.

661786656 is an abundant number, since it is smaller than the sum of its proper divisors (1075403568).

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

661786656 is a wasteful number, since it uses less digits than its factorization.

661786656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6893624 (or 6893616 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 51.

The square root of 661786656 is about 25725.2144014389. The cubic root of 661786656 is about 871.4437015174.

The spelling of 661786656 in words is "six hundred sixty-one million, seven hundred eighty-six thousand, six hundred fifty-six".