21504553320113 has 2 divisors, whose sum is σ = 21504553320114. Its totient is φ = 21504553320112.

The previous prime is 21504553320079. The next prime is 21504553320139. The reversal of 21504553320113 is 31102335540512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14735986207504 + 6768567112609 = 3838748^2 + 2601647^2 .

It is a cyclic number.

It is not a de Polignac number, because 21504553320113 - 2⁸ = 21504553319857 is a prime.

It is not a weakly prime, because it can be changed into another prime (21504553322113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10752276660056 + 10752276660057.

It is an arithmetic number, because the mean of its divisors is an integer number (10752276660057).

Almost surely, 2^{21504553320113} is an apocalyptic number.

It is an amenable number.

21504553320113 is a deficient number, since it is larger than the sum of its proper divisors (1).

21504553320113 is an equidigital number, since it uses as much as digits as its factorization.

21504553320113 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54000, while the sum is 35.

Adding to 21504553320113 its reverse (31102335540512), we get a palindrome (52606888860625).

The spelling of 21504553320113 in words is "twenty-one trillion, five hundred four billion, five hundred fifty-three million, three hundred twenty thousand, one hundred thirteen".