166918621 has 4 divisors (see below), whose sum is σ = 166977244. Its totient is φ = 166860000.

The previous prime is 166918579. The next prime is 166918627. The reversal of 166918621 is 126819661.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 43375396 + 123543225 = 6586^2 + 11115^2 .

It is a cyclic number.

It is not a de Polignac number, because 166918621 - 2⁹ = 166918109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166918627) 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 3 ways as a sum of consecutive naturals, for example, 24810 + ... + 30811.

It is an arithmetic number, because the mean of its divisors is an integer number (41744311).

Almost surely, 2^166918621 is an apocalyptic number.

It is an amenable number.

166918621 is a deficient number, since it is larger than the sum of its proper divisors (58623).

166918621 is an equidigital number, since it uses as much as digits as its factorization.

166918621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58622.

The product of its digits is 31104, while the sum is 40.

The square root of 166918621 is about 12919.6989516010. The cubic root of 166918621 is about 550.5983801529.

The spelling of 166918621 in words is "one hundred sixty-six million, nine hundred eighteen thousand, six hundred twenty-one".