166389521 has 16 divisors (see below), whose sum is σ = 179722368. Its totient is φ = 153648000.

The previous prime is 166389469. The next prime is 166389527. The reversal of 166389521 is 125983661.

It is a cyclic number.

It is not a de Polignac number, because 166389521 - 2²² = 162195217 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (166389527) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 94370 + ... + 96116.

It is an arithmetic number, because the mean of its divisors is an integer number (11232648).

Almost surely, 2^166389521 is an apocalyptic number.

It is an amenable number.

166389521 is a deficient number, since it is larger than the sum of its proper divisors (13332847).

166389521 is a wasteful number, since it uses less digits than its factorization.

166389521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1912.

The product of its digits is 77760, while the sum is 41.

The square root of 166389521 is about 12899.2062158879. The cubic root of 166389521 is about 550.0160006364.

The spelling of 166389521 in words is "one hundred sixty-six million, three hundred eighty-nine thousand, five hundred twenty-one".