21449490991 has 2 divisors, whose sum is σ = 21449490992. Its totient is φ = 21449490990.

The previous prime is 21449490973. The next prime is 21449491027. The reversal of 21449490991 is 19909494412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21449490991 - 2⁷ = 21449490863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21449490091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10724745495 + 10724745496.

It is an arithmetic number, because the mean of its divisors is an integer number (10724745496).

Almost surely, 2^21449490991 is an apocalyptic number.

21449490991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21449490991 is an equidigital number, since it uses as much as digits as its factorization.

21449490991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 839808, while the sum is 52.

The spelling of 21449490991 in words is "twenty-one billion, four hundred forty-nine million, four hundred ninety thousand, nine hundred ninety-one".