661656165156 has 216 divisors, whose sum is σ = 1989780339456. Its totient is φ = 184761642240.

The previous prime is 661656165143. The next prime is 661656165161. The reversal of 661656165156 is 651561656166.

661656165156 is a `hidden beast` number, since 6 + 6 + 1 + 6 + 5 + 616 + 5 + 15 + 6 = 666.

661656165156 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 63087745 + ... + 63098231.

It is an arithmetic number, because the mean of its divisors is an integer number (9211946016).

Almost surely, 2^661656165156 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661656165156, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (994890169728).

661656165156 is an abundant number, since it is smaller than the sum of its proper divisors (1328124174300).

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

661656165156 is a wasteful number, since it uses less digits than its factorization.

661656165156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11319 (or 11307 counting only the distinct ones).

The product of its digits is 5832000, while the sum is 54.

The spelling of 661656165156 in words is "six hundred sixty-one billion, six hundred fifty-six million, one hundred sixty-five thousand, one hundred fifty-six".