161811055 has 16 divisors (see below), whose sum is σ = 222788160. Its totient is φ = 110518272.

The previous prime is 161811037. The next prime is 161811109. The reversal of 161811055 is 550118161.

161811055 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

161811055 is a nontrivial binomial coefficient, being equal to C(17990, 2).

It is a 13-Lehmer number, since φ(161811055) divides (161811055-1)¹³.

It is a cyclic number.

It is not a de Polignac number, because 161811055 - 2⁷ = 161810927 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1 + ... + 17989.

It is an arithmetic number, because the mean of its divisors is an integer number (13924260).

Almost surely, 2^161811055 is an apocalyptic number.

161811055 is the 17989-th triangular number and also the 8995-th hexagonal number.

161811055 is the 5997-th centered nonagonal number.

161811055 is a deficient number, since it is larger than the sum of its proper divisors (60977105).

161811055 is a wasteful number, since it uses less digits than its factorization.

161811055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18258.

The product of its (nonzero) digits is 1200, while the sum is 28.

The square root of 161811055 is about 12720.4974352421. The cubic root of 161811055 is about 544.9241596906.

The spelling of 161811055 in words is "one hundred sixty-one million, eight hundred eleven thousand, fifty-five".