166642691 has 2 divisors, whose sum is σ = 166642692. Its totient is φ = 166642690.

The previous prime is 166642661. The next prime is 166642699. The reversal of 166642691 is 196246661.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166642691 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (166642699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83321345 + 83321346.

It is an arithmetic number, because the mean of its divisors is an integer number (83321346).

Almost surely, 2^166642691 is an apocalyptic number.

166642691 is a deficient number, since it is larger than the sum of its proper divisors (1).

166642691 is an equidigital number, since it uses as much as digits as its factorization.

166642691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 93312, while the sum is 41.

The square root of 166642691 is about 12909.0158803838. The cubic root of 166642691 is about 550.2948182479.

The spelling of 166642691 in words is "one hundred sixty-six million, six hundred forty-two thousand, six hundred ninety-one".