2158664021 has 2 divisors, whose sum is σ = 2158664022. Its totient is φ = 2158664020.

The previous prime is 2158664017. The next prime is 2158664033. The reversal of 2158664021 is 1204668512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1867449796 + 291214225 = 43214^2 + 17065^2 .

It is a cyclic number.

It is not a de Polignac number, because 2158664021 - 2² = 2158664017 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2158664041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1079332010 + 1079332011.

It is an arithmetic number, because the mean of its divisors is an integer number (1079332011).

Almost surely, 2^2158664021 is an apocalyptic number.

It is an amenable number.

2158664021 is a deficient number, since it is larger than the sum of its proper divisors (1).

2158664021 is an equidigital number, since it uses as much as digits as its factorization.

2158664021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23040, while the sum is 35.

The square root of 2158664021 is about 46461.4250857634. The cubic root of 2158664021 is about 1292.3942516932.

The spelling of 2158664021 in words is "two billion, one hundred fifty-eight million, six hundred sixty-four thousand, twenty-one".