21321898891 has 2 divisors, whose sum is σ = 21321898892. Its totient is φ = 21321898890.

The previous prime is 21321898889. The next prime is 21321898931. The reversal of 21321898891 is 19889812312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21321898891 - 2¹ = 21321898889 is a prime.

Together with 21321898889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21321898691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660949445 + 10660949446.

It is an arithmetic number, because the mean of its divisors is an integer number (10660949446).

Almost surely, 2^21321898891 is an apocalyptic number.

21321898891 is a deficient number, since it is larger than the sum of its proper divisors (1).

21321898891 is an equidigital number, since it uses as much as digits as its factorization.

21321898891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 497664, while the sum is 52.

The spelling of 21321898891 in words is "twenty-one billion, three hundred twenty-one million, eight hundred ninety-eight thousand, eight hundred ninety-one".