161955091 has 4 divisors (see below), whose sum is σ = 165400992. Its totient is φ = 158509192.

The previous prime is 161955049. The next prime is 161955109. The reversal of 161955091 is 190559161.

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

It is not a de Polignac number, because 161955091 - 2²⁷ = 27737363 is a prime.

It is a super-3 number, since 3×161955091³ (a number of 26 digits) contains 333 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 161955091.

It is not an unprimeable number, because it can be changed into a prime (161905091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1722880 + ... + 1722973.

It is an arithmetic number, because the mean of its divisors is an integer number (41350248).

Almost surely, 2^161955091 is an apocalyptic number.

161955091 is a deficient number, since it is larger than the sum of its proper divisors (3445901).

161955091 is an equidigital number, since it uses as much as digits as its factorization.

161955091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3445900.

The product of its (nonzero) digits is 12150, while the sum is 37.

The square root of 161955091 is about 12726.1577469400. The cubic root of 161955091 is about 545.0857996949.

The spelling of 161955091 in words is "one hundred sixty-one million, nine hundred fifty-five thousand, ninety-one".