166561371 has 12 divisors (see below), whose sum is σ = 240810648. Its totient is φ = 110938464.

The previous prime is 166561327. The next prime is 166561411. The reversal of 166561371 is 173165661.

166561371 is a `hidden beast` number, since 1 + 66 + 561 + 37 + 1 = 666.

It is not a de Polignac number, because 166561371 - 2¹⁹ = 166037083 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (166561301) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2511 + ... + 18423.

It is an arithmetic number, because the mean of its divisors is an integer number (20067554).

Almost surely, 2^166561371 is an apocalyptic number.

166561371 is a deficient number, since it is larger than the sum of its proper divisors (74249277).

166561371 is a wasteful number, since it uses less digits than its factorization.

166561371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17082 (or 17079 counting only the distinct ones).

The product of its digits is 22680, while the sum is 36.

The square root of 166561371 is about 12905.8657594134. The cubic root of 166561371 is about 550.2052908575.

It can be divided in two parts, 1665 and 61371, that added together give a palindrome (63036).

The spelling of 166561371 in words is "one hundred sixty-six million, five hundred sixty-one thousand, three hundred seventy-one".