166561939 has 2 divisors, whose sum is σ = 166561940. Its totient is φ = 166561938.

The previous prime is 166561873. The next prime is 166561949. The reversal of 166561939 is 939165661.

166561939 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 is a cyclic number.

It is not a de Polignac number, because 166561939 - 2¹⁵ = 166529171 is a prime.

It is not a weakly prime, because it can be changed into another prime (166561949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83280969 + 83280970.

It is an arithmetic number, because the mean of its divisors is an integer number (83280970).

Almost surely, 2^166561939 is an apocalyptic number.

166561939 is a deficient number, since it is larger than the sum of its proper divisors (1).

166561939 is an equidigital number, since it uses as much as digits as its factorization.

166561939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 262440, while the sum is 46.

The square root of 166561939 is about 12905.8877648924. The cubic root of 166561939 is about 550.2059162851.

The spelling of 166561939 in words is "one hundred sixty-six million, five hundred sixty-one thousand, nine hundred thirty-nine".