161581956 has 12 divisors (see below), whose sum is σ = 377024592. Its totient is φ = 53860648.

The previous prime is 161581919. The next prime is 161581967. The reversal of 161581956 is 659185161.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×161581956² = 52217457009571872, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6732570 + ... + 6732593.

It is an arithmetic number, because the mean of its divisors is an integer number (31418716).

Almost surely, 2^161581956 is an apocalyptic number.

It is an amenable number.

161581956 is an abundant number, since it is smaller than the sum of its proper divisors (215442636).

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

161581956 is a wasteful number, since it uses less digits than its factorization.

161581956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13465170 (or 13465168 counting only the distinct ones).

The product of its digits is 64800, while the sum is 42.

The square root of 161581956 is about 12711.4891338505. The cubic root of 161581956 is about 544.6668625916. Note that the first 3 decimals are identical.

The spelling of 161581956 in words is "one hundred sixty-one million, five hundred eighty-one thousand, nine hundred fifty-six".