21021222120991 has 2 divisors, whose sum is σ = 21021222120992. Its totient is φ = 21021222120990.

The previous prime is 21021222120923. The next prime is 21021222121001. The reversal of 21021222120991 is 19902122212012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21021222120991 - 2²³ = 21021213732383 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021222120791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510611060495 + 10510611060496.

It is an arithmetic number, because the mean of its divisors is an integer number (10510611060496).

Almost surely, 2^{21021222120991} is an apocalyptic number.

21021222120991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021222120991 is an equidigital number, since it uses as much as digits as its factorization.

21021222120991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 34.

The spelling of 21021222120991 in words is "twenty-one trillion, twenty-one billion, two hundred twenty-two million, one hundred twenty thousand, nine hundred ninety-one".