166505639 has 2 divisors, whose sum is σ = 166505640. Its totient is φ = 166505638.

The previous prime is 166505629. The next prime is 166505663. The reversal of 166505639 is 936505661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 166505639 - 2⁴ = 166505623 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 166505596 and 166505605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166505609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83252819 + 83252820.

It is an arithmetic number, because the mean of its divisors is an integer number (83252820).

Almost surely, 2^166505639 is an apocalyptic number.

166505639 is a deficient number, since it is larger than the sum of its proper divisors (1).

166505639 is an equidigital number, since it uses as much as digits as its factorization.

166505639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145800, while the sum is 41.

The square root of 166505639 is about 12903.7064055255. The cubic root of 166505639 is about 550.1439171592.

The spelling of 166505639 in words is "one hundred sixty-six million, five hundred five thousand, six hundred thirty-nine".