166165591 has 2 divisors, whose sum is σ = 166165592. Its totient is φ = 166165590.

The previous prime is 166165567. The next prime is 166165603. The reversal of 166165591 is 195561661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 166165591 - 2⁹ = 166165079 is a prime.

It is a super-2 number, since 2×166165591² = 55222007264758562, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166165291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83082795 + 83082796.

It is an arithmetic number, because the mean of its divisors is an integer number (83082796).

Almost surely, 2^166165591 is an apocalyptic number.

166165591 is a deficient number, since it is larger than the sum of its proper divisors (1).

166165591 is an equidigital number, since it uses as much as digits as its factorization.

166165591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48600, while the sum is 40.

The square root of 166165591 is about 12890.5233020231. The cubic root of 166165591 is about 549.7691494000.

The spelling of 166165591 in words is "one hundred sixty-six million, one hundred sixty-five thousand, five hundred ninety-one".