2155691 has 2 divisors, whose sum is σ = 2155692. Its totient is φ = 2155690.

The previous prime is 2155667. The next prime is 2155711. The reversal of 2155691 is 1965512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2155691 - 2⁶ = 2155627 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (2155661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1077845 + 1077846.

It is an arithmetic number, because the mean of its divisors is an integer number (1077846).

2^2155691 is an apocalyptic number.

2155691 is a deficient number, since it is larger than the sum of its proper divisors (1).

2155691 is an equidigital number, since it uses as much as digits as its factorization.

2155691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2700, while the sum is 29.

The square root of 2155691 is about 1468.2271622607. The cubic root of 2155691 is about 129.1800662247.

The spelling of 2155691 in words is "two million, one hundred fifty-five thousand, six hundred ninety-one".