2166691 has 2 divisors, whose sum is σ = 2166692. Its totient is φ = 2166690.

The previous prime is 2166679. The next prime is 2166709. The reversal of 2166691 is 1966612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2166691 - 2⁹ = 2166179 is a prime.

It is not a weakly prime, because it can be changed into another prime (2166601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1083345 + 1083346.

It is an arithmetic number, because the mean of its divisors is an integer number (1083346).

2^2166691 is an apocalyptic number.

2166691 is a deficient number, since it is larger than the sum of its proper divisors (1).

2166691 is an equidigital number, since it uses as much as digits as its factorization.

2166691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 31.

The square root of 2166691 is about 1471.9684099871. The cubic root of 2166691 is about 129.3994190256.

The spelling of 2166691 in words is "two million, one hundred sixty-six thousand, six hundred ninety-one".