661601656156 has 12 divisors (see below), whose sum is σ = 1323203312368. Its totient is φ = 283543566912.

The previous prime is 661601656151. The next prime is 661601656231. The reversal of 661601656156 is 651656106166.

661601656156 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661601656151) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11814315261 + ... + 11814315316.

Almost surely, 2^661601656156 is an apocalyptic number.

It is an amenable number.

661601656156 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

661601656156 is a wasteful number, since it uses less digits than its factorization.

661601656156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23628630588 (or 23628630586 counting only the distinct ones).

The product of its (nonzero) digits is 1166400, while the sum is 49.

The spelling of 661601656156 in words is "six hundred sixty-one billion, six hundred one million, six hundred fifty-six thousand, one hundred fifty-six".