661561677 has 24 divisors (see below), whose sum is σ = 1096160000. Its totient is φ = 376630560.

The previous prime is 661561661. The next prime is 661561723. The reversal of 661561677 is 776165166.

It is not a de Polignac number, because 661561677 - 2⁴ = 661561661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661561877) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2302 + ... + 36447.

Almost surely, 2^661561677 is an apocalyptic number.

It is an amenable number.

661561677 is a deficient number, since it is larger than the sum of its proper divisors (434598323).

661561677 is a wasteful number, since it uses less digits than its factorization.

661561677 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39033 (or 39030 counting only the distinct ones).

The product of its digits is 317520, while the sum is 45.

The square root of 661561677 is about 25720.8412965051. The cubic root of 661561677 is about 871.3449391988.

The spelling of 661561677 in words is "six hundred sixty-one million, five hundred sixty-one thousand, six hundred seventy-seven".