161561508372 has 36 divisors (see below), whose sum is σ = 445518099936. Its totient is φ = 48958032720.

The previous prime is 161561508359. The next prime is 161561508389. The reversal of 161561508372 is 273805165161.

161561508372 is a `hidden beast` number, since 1 + 6 + 1 + 561 + 5 + 0 + 83 + 7 + 2 = 666.

161561508372 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×161561508372² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 203991408 + ... + 203992199.

It is an arithmetic number, because the mean of its divisors is an integer number (12375502776).

Almost surely, 2^161561508372 is an apocalyptic number.

161561508372 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

161561508372 is an abundant number, since it is smaller than the sum of its proper divisors (283956591564).

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

161561508372 is a wasteful number, since it uses less digits than its factorization.

161561508372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407983628 (or 407983623 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The spelling of 161561508372 in words is "one hundred sixty-one billion, five hundred sixty-one million, five hundred eight thousand, three hundred seventy-two".