21115503245591 has 2 divisors, whose sum is σ = 21115503245592. Its totient is φ = 21115503245590.

The previous prime is 21115503245549. The next prime is 21115503245593. The reversal of 21115503245591 is 19554230551112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21115503245591 - 2³⁸ = 20840625338647 is a prime.

Together with 21115503245593, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21115503245593) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10557751622795 + 10557751622796.

It is an arithmetic number, because the mean of its divisors is an integer number (10557751622796).

Almost surely, 2^{21115503245591} is an apocalyptic number.

21115503245591 is a deficient number, since it is larger than the sum of its proper divisors (1).

21115503245591 is an equidigital number, since it uses as much as digits as its factorization.

21115503245591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 270000, while the sum is 44.

The spelling of 21115503245591 in words is "twenty-one trillion, one hundred fifteen billion, five hundred three million, two hundred forty-five thousand, five hundred ninety-one".