2118947921 has 2 divisors, whose sum is σ = 2118947922. Its totient is φ = 2118947920.

The previous prime is 2118947891. The next prime is 2118947939. The reversal of 2118947921 is 1297498112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1280208400 + 838739521 = 35780^2 + 28961^2 .

It is a cyclic number.

It is not a de Polignac number, because 2118947921 - 2²² = 2114753617 is a prime.

It is not a weakly prime, because it can be changed into another prime (2118947951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1059473960 + 1059473961.

It is an arithmetic number, because the mean of its divisors is an integer number (1059473961).

Almost surely, 2^2118947921 is an apocalyptic number.

It is an amenable number.

2118947921 is a deficient number, since it is larger than the sum of its proper divisors (1).

2118947921 is an equidigital number, since it uses as much as digits as its factorization.

2118947921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 44.

The square root of 2118947921 is about 46032.0314672294. The cubic root of 2118947921 is about 1284.4191172056.

The spelling of 2118947921 in words is "two billion, one hundred eighteen million, nine hundred forty-seven thousand, nine hundred twenty-one".