166188891 has 16 divisors (see below), whose sum is σ = 242104320. Its totient is φ = 100564320.

The previous prime is 166188871. The next prime is 166188901. The reversal of 166188891 is 198881661.

It is not a de Polignac number, because 166188891 - 2¹¹ = 166186843 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 166188891.

It is not an unprimeable number, because it can be changed into a prime (166188871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19846 + ... + 26948.

It is an arithmetic number, because the mean of its divisors is an integer number (15131520).

Almost surely, 2^166188891 is an apocalyptic number.

166188891 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

166188891 is a deficient number, since it is larger than the sum of its proper divisors (75915429).

166188891 is a wasteful number, since it uses less digits than its factorization.

166188891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7826.

The product of its digits is 165888, while the sum is 48.

The square root of 166188891 is about 12891.4270350493. The cubic root of 166188891 is about 549.7948446967.

The spelling of 166188891 in words is "one hundred sixty-six million, one hundred eighty-eight thousand, eight hundred ninety-one".