21515417113 has 2 divisors, whose sum is σ = 21515417114. Its totient is φ = 21515417112.

The previous prime is 21515417089. The next prime is 21515417149. The reversal of 21515417113 is 31171451512.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17622031504 + 3893385609 = 132748^2 + 62397^2 .

It is a cyclic number.

It is not a de Polignac number, because 21515417113 - 2⁵ = 21515417081 is a prime.

It is not a weakly prime, because it can be changed into another prime (21515417153) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757708556 + 10757708557.

It is an arithmetic number, because the mean of its divisors is an integer number (10757708557).

Almost surely, 2^21515417113 is an apocalyptic number.

It is an amenable number.

21515417113 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515417113 is an equidigital number, since it uses as much as digits as its factorization.

21515417113 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4200, while the sum is 31.

Adding to 21515417113 its reverse (31171451512), we get a palindrome (52686868625).

The spelling of 21515417113 in words is "twenty-one billion, five hundred fifteen million, four hundred seventeen thousand, one hundred thirteen".