21338808991 has 2 divisors, whose sum is σ = 21338808992. Its totient is φ = 21338808990.

The previous prime is 21338808977. The next prime is 21338809021. The reversal of 21338808991 is 19980883312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21338808991 - 2⁹ = 21338808479 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21338808691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10669404495 + 10669404496.

It is an arithmetic number, because the mean of its divisors is an integer number (10669404496).

Almost surely, 2^21338808991 is an apocalyptic number.

21338808991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21338808991 is an equidigital number, since it uses as much as digits as its factorization.

21338808991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 746496, while the sum is 52.

The spelling of 21338808991 in words is "twenty-one billion, three hundred thirty-eight million, eight hundred eight thousand, nine hundred ninety-one".