21313101521 has 2 divisors, whose sum is σ = 21313101522. Its totient is φ = 21313101520.

The previous prime is 21313101517. The next prime is 21313101533. The reversal of 21313101521 is 12510131312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18048579025 + 3264522496 = 134345^2 + 57136^2 .

It is a cyclic number.

It is not a de Polignac number, because 21313101521 - 2² = 21313101517 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21313101493 and 21313101502.

It is not a weakly prime, because it can be changed into another prime (21313101541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656550760 + 10656550761.

It is an arithmetic number, because the mean of its divisors is an integer number (10656550761).

Almost surely, 2^21313101521 is an apocalyptic number.

It is an amenable number.

21313101521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21313101521 is an equidigital number, since it uses as much as digits as its factorization.

21313101521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 180, while the sum is 20.

Adding to 21313101521 its reverse (12510131312), we get a palindrome (33823232833).

The spelling of 21313101521 in words is "twenty-one billion, three hundred thirteen million, one hundred one thousand, five hundred twenty-one".