21515919053 has 2 divisors, whose sum is σ = 21515919054. Its totient is φ = 21515919052.

The previous prime is 21515918999. The next prime is 21515919059. The reversal of 21515919053 is 35091951512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15629500324 + 5886418729 = 125018^2 + 76723^2 .

It is a cyclic number.

It is not a de Polignac number, because 21515919053 - 2²⁰ = 21514870477 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21515919053.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21515919059) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757959526 + 10757959527.

It is an arithmetic number, because the mean of its divisors is an integer number (10757959527).

Almost surely, 2^21515919053 is an apocalyptic number.

It is an amenable number.

21515919053 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515919053 is an equidigital number, since it uses as much as digits as its factorization.

21515919053 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 60750, while the sum is 41.

The spelling of 21515919053 in words is "twenty-one billion, five hundred fifteen million, nine hundred nineteen thousand, fifty-three".