166066991 has 2 divisors, whose sum is σ = 166066992. Its totient is φ = 166066990.

The previous prime is 166066987. The next prime is 166067023. The reversal of 166066991 is 199660661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 166066991 - 2² = 166066987 is a prime.

It is a Sophie Germain 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 (166066951) 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, 83033495 + 83033496.

It is an arithmetic number, because the mean of its divisors is an integer number (83033496).

Almost surely, 2^166066991 is an apocalyptic number.

166066991 is a deficient number, since it is larger than the sum of its proper divisors (1).

166066991 is an equidigital number, since it uses as much as digits as its factorization.

166066991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 104976, while the sum is 44.

The square root of 166066991 is about 12886.6982194820. The cubic root of 166066991 is about 549.6603864822.

The spelling of 166066991 in words is "one hundred sixty-six million, sixty-six thousand, nine hundred ninety-one".