21115351513 has 2 divisors, whose sum is σ = 21115351514. Its totient is φ = 21115351512.

The previous prime is 21115351487. The next prime is 21115351571. The reversal of 21115351513 is 31515351112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10578739609 + 10536611904 = 102853^2 + 102648^2 .

It is a cyclic number.

It is not a de Polignac number, because 21115351513 - 2²¹ = 21113254361 is a prime.

It is not a weakly prime, because it can be changed into another prime (21115351583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10557675756 + 10557675757.

It is an arithmetic number, because the mean of its divisors is an integer number (10557675757).

Almost surely, 2^21115351513 is an apocalyptic number.

It is an amenable number.

21115351513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21115351513 is an equidigital number, since it uses as much as digits as its factorization.

21115351513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2250, while the sum is 28.

The spelling of 21115351513 in words is "twenty-one billion, one hundred fifteen million, three hundred fifty-one thousand, five hundred thirteen".