161661511056 has 80 divisors (see below), whose sum is σ = 432225460800. Its totient is φ = 52005026304.

The previous prime is 161661510971. The next prime is 161661511079. The reversal of 161661511056 is 650115166161.

It is a super-2 number, since 2×161661511056² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3130050 + ... + 3181278.

It is an arithmetic number, because the mean of its divisors is an integer number (5402818260).

Almost surely, 2^161661511056 is an apocalyptic number.

161661511056 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161661511056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (216112730400).

161661511056 is an abundant number, since it is smaller than the sum of its proper divisors (270563949744).

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

161661511056 is a wasteful number, since it uses less digits than its factorization.

161661511056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53536 (or 53530 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 39.

The spelling of 161661511056 in words is "one hundred sixty-one billion, six hundred sixty-one million, five hundred eleven thousand, fifty-six".