21495316321 has 2 divisors, whose sum is σ = 21495316322. Its totient is φ = 21495316320.

The previous prime is 21495316313. The next prime is 21495316327. The reversal of 21495316321 is 12361359412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16822090000 + 4673226321 = 129700^2 + 68361^2 .

It is a cyclic number.

It is not a de Polignac number, because 21495316321 - 2³ = 21495316313 is a prime.

It is not a weakly prime, because it can be changed into another prime (21495316327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10747658160 + 10747658161.

It is an arithmetic number, because the mean of its divisors is an integer number (10747658161).

Almost surely, 2^21495316321 is an apocalyptic number.

It is an amenable number.

21495316321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21495316321 is an equidigital number, since it uses as much as digits as its factorization.

21495316321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 37.

The spelling of 21495316321 in words is "twenty-one billion, four hundred ninety-five million, three hundred sixteen thousand, three hundred twenty-one".