166556399 has 2 divisors, whose sum is σ = 166556400. Its totient is φ = 166556398.

The previous prime is 166556389. The next prime is 166556407. The reversal of 166556399 is 993655661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 166556399 - 2²⁴ = 149779183 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166556389) 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 as a sum of consecutive naturals, namely, 83278199 + 83278200.

It is an arithmetic number, because the mean of its divisors is an integer number (83278200).

Almost surely, 2^166556399 is an apocalyptic number.

166556399 is a deficient number, since it is larger than the sum of its proper divisors (1).

166556399 is an equidigital number, since it uses as much as digits as its factorization.

166556399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1312200, while the sum is 50.

The square root of 166556399 is about 12905.6731323864. The cubic root of 166556399 is about 550.1998161029.

The spelling of 166556399 in words is "one hundred sixty-six million, five hundred fifty-six thousand, three hundred ninety-nine".