161555511 has 32 divisors (see below), whose sum is σ = 239984640. Its totient is φ = 96048000.

The previous prime is 161555509. The next prime is 161555521. The reversal of 161555511 is 115555161.

It is not a de Polignac number, because 161555511 - 2¹ = 161555509 is a prime.

It is a super-2 number, since 2×161555511² = 52200366268942242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161555521) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 139786 + ... + 140936.

It is an arithmetic number, because the mean of its divisors is an integer number (7499520).

Almost surely, 2^161555511 is an apocalyptic number.

161555511 is a deficient number, since it is larger than the sum of its proper divisors (78429129).

161555511 is a wasteful number, since it uses less digits than its factorization.

161555511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1287.

The product of its digits is 3750, while the sum is 30.

The square root of 161555511 is about 12710.4488905782. The cubic root of 161555511 is about 544.6371470190.

The spelling of 161555511 in words is "one hundred sixty-one million, five hundred fifty-five thousand, five hundred eleven".