21221222010991 has 2 divisors, whose sum is σ = 21221222010992. Its totient is φ = 21221222010990.

The previous prime is 21221222010983. The next prime is 21221222011001. The reversal of 21221222010991 is 19901022212212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21221222010991 - 2³ = 21221222010983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221222017991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610611005495 + 10610611005496.

It is an arithmetic number, because the mean of its divisors is an integer number (10610611005496).

Almost surely, 2^{21221222010991} is an apocalyptic number.

21221222010991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221222010991 is an equidigital number, since it uses as much as digits as its factorization.

21221222010991 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 21221222010991 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty-two million, ten thousand, nine hundred ninety-one".