21398712553 has 2 divisors, whose sum is σ = 21398712554. Its totient is φ = 21398712552.

The previous prime is 21398712521. The next prime is 21398712563. The reversal of 21398712553 is 35521789312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11887977024 + 9510735529 = 109032^2 + 97523^2 .

It is a cyclic number.

It is not a de Polignac number, because 21398712553 - 2⁵ = 21398712521 is a prime.

It is not a weakly prime, because it can be changed into another prime (21398712563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10699356276 + 10699356277.

It is an arithmetic number, because the mean of its divisors is an integer number (10699356277).

Almost surely, 2^21398712553 is an apocalyptic number.

It is an amenable number.

21398712553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21398712553 is an equidigital number, since it uses as much as digits as its factorization.

21398712553 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 453600, while the sum is 46.

The spelling of 21398712553 in words is "twenty-one billion, three hundred ninety-eight million, seven hundred twelve thousand, five hundred fifty-three".