161555131 has 4 divisors (see below), whose sum is σ = 171058392. Its totient is φ = 152051872.

The previous prime is 161555123. The next prime is 161555179. The reversal of 161555131 is 131555161.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 161555131 - 2³ = 161555123 is a prime.

It is a super-2 number, since 2×161555131² = 52200120704854322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161555131.

It is not an unprimeable number, because it can be changed into a prime (161555111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4751605 + ... + 4751638.

It is an arithmetic number, because the mean of its divisors is an integer number (42764598).

Almost surely, 2^161555131 is an apocalyptic number.

161555131 is a deficient number, since it is larger than the sum of its proper divisors (9503261).

161555131 is an equidigital number, since it uses as much as digits as its factorization.

161555131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9503260.

The product of its digits is 2250, while the sum is 28.

The square root of 161555131 is about 12710.4339422382. The cubic root of 161555131 is about 544.6367199990.

The spelling of 161555131 in words is "one hundred sixty-one million, five hundred fifty-five thousand, one hundred thirty-one".