166901809 has 2 divisors, whose sum is σ = 166901810. Its totient is φ = 166901808.

The previous prime is 166901773. The next prime is 166901821. The reversal of 166901809 is 908109661.

166901809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 100560784 + 66341025 = 10028^2 + 8145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166901809 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (166901309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83450904 + 83450905.

It is an arithmetic number, because the mean of its divisors is an integer number (83450905).

Almost surely, 2^166901809 is an apocalyptic number.

It is an amenable number.

166901809 is a deficient number, since it is larger than the sum of its proper divisors (1).

166901809 is an equidigital number, since it uses as much as digits as its factorization.

166901809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 166901809 is about 12919.0483008618. The cubic root of 166901809 is about 550.5798941571.

The spelling of 166901809 in words is "one hundred sixty-six million, nine hundred one thousand, eight hundred nine".