21884291921 has 2 divisors, whose sum is σ = 21884291922. Its totient is φ = 21884291920.

The previous prime is 21884291899. The next prime is 21884291939. The reversal of 21884291921 is 12919248812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20431843600 + 1452448321 = 142940^2 + 38111^2 .

It is a cyclic number.

It is not a de Polignac number, because 21884291921 - 2¹⁴ = 21884275537 is a prime.

It is not a weakly prime, because it can be changed into another prime (21884291971) 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, 10942145960 + 10942145961.

It is an arithmetic number, because the mean of its divisors is an integer number (10942145961).

Almost surely, 2^21884291921 is an apocalyptic number.

It is an amenable number.

21884291921 is a deficient number, since it is larger than the sum of its proper divisors (1).

21884291921 is an equidigital number, since it uses as much as digits as its factorization.

21884291921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 165888, while the sum is 47.

The spelling of 21884291921 in words is "twenty-one billion, eight hundred eighty-four million, two hundred ninety-one thousand, nine hundred twenty-one".