21012222991 has 2 divisors, whose sum is σ = 21012222992. Its totient is φ = 21012222990.

The previous prime is 21012222967. The next prime is 21012223021. The reversal of 21012222991 is 19922221012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21012222991 - 2¹⁹ = 21011698703 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012222901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506111495 + 10506111496.

It is an arithmetic number, because the mean of its divisors is an integer number (10506111496).

Almost surely, 2^21012222991 is an apocalyptic number.

21012222991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012222991 is an equidigital number, since it uses as much as digits as its factorization.

21012222991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 31.

The spelling of 21012222991 in words is "twenty-one billion, twelve million, two hundred twenty-two thousand, nine hundred ninety-one".