661535756631 has 6 divisors (see below), whose sum is σ = 955551648480. Its totient is φ = 441023837748.

The previous prime is 661535756617. The next prime is 661535756701. The reversal of 661535756631 is 136657535166.

661535756631 is a `hidden beast` number, since 6 + 6 + 1 + 5 + 3 + 575 + 6 + 63 + 1 = 666.

It is not a de Polignac number, because 661535756631 - 2¹⁰ = 661535755607 is a prime.

It is a super-2 number, since 2×661535756631² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661535756611) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36751986471 + ... + 36751986488.

It is an arithmetic number, because the mean of its divisors is an integer number (159258608080).

Almost surely, 2^661535756631 is an apocalyptic number.

661535756631 is a deficient number, since it is larger than the sum of its proper divisors (294015891849).

661535756631 is a wasteful number, since it uses less digits than its factorization.

661535756631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73503972965 (or 73503972962 counting only the distinct ones).

The product of its digits is 10206000, while the sum is 54.

The spelling of 661535756631 in words is "six hundred sixty-one billion, five hundred thirty-five million, seven hundred fifty-six thousand, six hundred thirty-one".