161640799881 has 32 divisors (see below), whose sum is σ = 242934743040. Its totient is φ = 94711593600.

The previous prime is 161640799877. The next prime is 161640799883. The reversal of 161640799881 is 188997046161.

It is not a de Polignac number, because 161640799881 - 2² = 161640799877 is a prime.

It is a super-2 number, since 2×161640799881² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (161640799883) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 980280 + ... + 1133238.

It is an arithmetic number, because the mean of its divisors is an integer number (7591710720).

Almost surely, 2^161640799881 is an apocalyptic number.

161640799881 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

161640799881 is a deficient number, since it is larger than the sum of its proper divisors (81293943159).

161640799881 is a wasteful number, since it uses less digits than its factorization.

161640799881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154037.

The product of its (nonzero) digits is 5225472, while the sum is 60.

The spelling of 161640799881 in words is "one hundred sixty-one billion, six hundred forty million, seven hundred ninety-nine thousand, eight hundred eighty-one".