2157664991 has 2 divisors, whose sum is σ = 2157664992. Its totient is φ = 2157664990.

The previous prime is 2157664979. The next prime is 2157665071. The reversal of 2157664991 is 1994667512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2157664991 - 2¹⁰ = 2157663967 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2157664921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1078832495 + 1078832496.

It is an arithmetic number, because the mean of its divisors is an integer number (1078832496).

Almost surely, 2^2157664991 is an apocalyptic number.

2157664991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2157664991 is an equidigital number, since it uses as much as digits as its factorization.

2157664991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 816480, while the sum is 50.

The square root of 2157664991 is about 46450.6726646665. The cubic root of 2157664991 is about 1292.1948475173.

The spelling of 2157664991 in words is "two billion, one hundred fifty-seven million, six hundred sixty-four thousand, nine hundred ninety-one".