21115351591 has 2 divisors, whose sum is σ = 21115351592. Its totient is φ = 21115351590.

The previous prime is 21115351583. The next prime is 21115351613. The reversal of 21115351591 is 19515351112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21115351591 - 2³ = 21115351583 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21115351571) 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, 10557675795 + 10557675796.

It is an arithmetic number, because the mean of its divisors is an integer number (10557675796).

Almost surely, 2^21115351591 is an apocalyptic number.

21115351591 is a deficient number, since it is larger than the sum of its proper divisors (1).

21115351591 is an equidigital number, since it uses as much as digits as its factorization.

21115351591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6750, while the sum is 34.

The spelling of 21115351591 in words is "twenty-one billion, one hundred fifteen million, three hundred fifty-one thousand, five hundred ninety-one".