21311102521 has 2 divisors, whose sum is σ = 21311102522. Its totient is φ = 21311102520.

The previous prime is 21311102509. The next prime is 21311102531. The reversal of 21311102521 is 12520111312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21028190121 + 282912400 = 145011^2 + 16820^2 .

It is a cyclic number.

It is not a de Polignac number, because 21311102521 - 2²¹ = 21309005369 is a prime.

It is not a weakly prime, because it can be changed into another prime (21311102531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655551260 + 10655551261.

It is an arithmetic number, because the mean of its divisors is an integer number (10655551261).

Almost surely, 2^21311102521 is an apocalyptic number.

It is an amenable number.

21311102521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21311102521 is an equidigital number, since it uses as much as digits as its factorization.

21311102521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120, while the sum is 19.

Adding to 21311102521 its reverse (12520111312), we get a palindrome (33831213833).

The spelling of 21311102521 in words is "twenty-one billion, three hundred eleven million, one hundred two thousand, five hundred twenty-one".