21211222391 has 2 divisors, whose sum is σ = 21211222392. Its totient is φ = 21211222390.

The previous prime is 21211222231. The next prime is 21211222393. The reversal of 21211222391 is 19322211212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21211222391 - 2¹⁴ = 21211206007 is a prime.

Together with 21211222393, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21211222391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211222393) 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, 10605611195 + 10605611196.

It is an arithmetic number, because the mean of its divisors is an integer number (10605611196).

Almost surely, 2^21211222391 is an apocalyptic number.

21211222391 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211222391 is an equidigital number, since it uses as much as digits as its factorization.

21211222391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 26.

The spelling of 21211222391 in words is "twenty-one billion, two hundred eleven million, two hundred twenty-two thousand, three hundred ninety-one".