161261905920 has 96 divisors (see below), whose sum is σ = 515912211360. Its totient is φ = 43003166720.

The previous prime is 161261905919. The next prime is 161261905951. The reversal of 161261905920 is 29509162161.

It is a tau number, because it is divible by the number of its divisors (96).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2593986 + ... + 2655425.

It is an arithmetic number, because the mean of its divisors is an integer number (5374085535).

Almost surely, 2^161261905920 is an apocalyptic number.

161261905920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161261905920 is an abundant number, since it is smaller than the sum of its proper divisors (354650305440).

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

161261905920 is an equidigital number, since it uses as much as digits as its factorization.

161261905920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5249441 (or 5249421 counting only the distinct ones).

The product of its (nonzero) digits is 58320, while the sum is 42.

The spelling of 161261905920 in words is "one hundred sixty-one billion, two hundred sixty-one million, nine hundred five thousand, nine hundred twenty".