21115351013 has 2 divisors, whose sum is σ = 21115351014. Its totient is φ = 21115351012.

The previous prime is 21115350967. The next prime is 21115351021. The reversal of 21115351013 is 31015351112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20898171844 + 217179169 = 144562^2 + 14737^2 .

It is a cyclic number.

It is not a de Polignac number, because 21115351013 - 2³² = 16820383717 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21115351013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21115351513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10557675506 + 10557675507.

It is an arithmetic number, because the mean of its divisors is an integer number (10557675507).

Almost surely, 2^21115351013 is an apocalyptic number.

It is an amenable number.

21115351013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21115351013 is an equidigital number, since it uses as much as digits as its factorization.

21115351013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 450, while the sum is 23.

Subtracting 21115351013 from its reverse (31015351112), we obtain a palindrome (9900000099).

The spelling of 21115351013 in words is "twenty-one billion, one hundred fifteen million, three hundred fifty-one thousand, thirteen".