166665091 has 2 divisors, whose sum is σ = 166665092. Its totient is φ = 166665090.

The previous prime is 166665089. The next prime is 166665097. The reversal of 166665091 is 190566661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 166665091 - 2¹ = 166665089 is a prime.

Together with 166665089, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (166665097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83332545 + 83332546.

It is an arithmetic number, because the mean of its divisors is an integer number (83332546).

Almost surely, 2^166665091 is an apocalyptic number.

166665091 is a deficient number, since it is larger than the sum of its proper divisors (1).

166665091 is an equidigital number, since it uses as much as digits as its factorization.

166665091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 58320, while the sum is 40.

The square root of 166665091 is about 12909.8834619062. The cubic root of 166665091 is about 550.3194738981.

The spelling of 166665091 in words is "one hundred sixty-six million, six hundred sixty-five thousand, ninety-one".