161556505 has 8 divisors (see below), whose sum is σ = 211492224. Its totient is φ = 117495600.

The previous prime is 161556481. The next prime is 161556509. The reversal of 161556505 is 505655161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 161556505 - 2⁷ = 161556377 is a prime.

It is a super-2 number, since 2×161556505² = 52201008615630050, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161556509) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1468641 + ... + 1468750.

It is an arithmetic number, because the mean of its divisors is an integer number (26436528).

Almost surely, 2^161556505 is an apocalyptic number.

It is an amenable number.

161556505 is a deficient number, since it is larger than the sum of its proper divisors (49935719).

161556505 is a wasteful number, since it uses less digits than its factorization.

161556505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2937407.

The product of its (nonzero) digits is 22500, while the sum is 34.

The square root of 161556505 is about 12710.4879922055. The cubic root of 161556505 is about 544.6382640101.

The spelling of 161556505 in words is "one hundred sixty-one million, five hundred fifty-six thousand, five hundred five".