166921939 has 4 divisors (see below), whose sum is σ = 166951624. Its totient is φ = 166892256.

The previous prime is 166921927. The next prime is 166922009. The reversal of 166921939 is 939129661.

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

It is a cyclic number.

It is not a de Polignac number, because 166921939 - 2⁵ = 166921907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166921919) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3537 + ... + 18610.

It is an arithmetic number, because the mean of its divisors is an integer number (41737906).

Almost surely, 2^166921939 is an apocalyptic number.

166921939 is a deficient number, since it is larger than the sum of its proper divisors (29685).

166921939 is an equidigital number, since it uses as much as digits as its factorization.

166921939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29684.

The product of its digits is 157464, while the sum is 46.

The square root of 166921939 is about 12919.8273595277. The cubic root of 166921939 is about 550.6020283844.

The spelling of 166921939 in words is "one hundred sixty-six million, nine hundred twenty-one thousand, nine hundred thirty-nine".