161605666 has 16 divisors (see below), whose sum is σ = 253048320. Its totient is φ = 77315040.

The previous prime is 161605657. The next prime is 161605681. The reversal of 161605666 is 666506161.

It is a super-2 number, since 2×161605666² = 52232782566607112, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9126 + ... + 20161.

It is an arithmetic number, because the mean of its divisors is an integer number (15815520).

Almost surely, 2^161605666 is an apocalyptic number.

161605666 is a deficient number, since it is larger than the sum of its proper divisors (91442654).

161605666 is a wasteful number, since it uses less digits than its factorization.

161605666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29409.

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 161605666 is about 12712.4217205063. The cubic root of 161605666 is about 544.6935021579.

The spelling of 161605666 in words is "one hundred sixty-one million, six hundred five thousand, six hundred sixty-six".