21513035065 has 4 divisors (see below), whose sum is σ = 25815642084. Its totient is φ = 17210428048.

The previous prime is 21513035059. The next prime is 21513035069. The reversal of 21513035065 is 56053031512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5084973481 + 16428061584 = 71309^2 + 128172^2 .

It is a cyclic number.

It is not a de Polignac number, because 21513035065 - 2⁹ = 21513034553 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21513035069) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2151303502 + ... + 2151303511.

It is an arithmetic number, because the mean of its divisors is an integer number (6453910521).

Almost surely, 2^21513035065 is an apocalyptic number.

It is an amenable number.

21513035065 is a deficient number, since it is larger than the sum of its proper divisors (4302607019).

21513035065 is an equidigital number, since it uses as much as digits as its factorization.

21513035065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4302607018.

The product of its (nonzero) digits is 13500, while the sum is 31.

Adding to 21513035065 its reverse (56053031512), we get a palindrome (77566066577).

The spelling of 21513035065 in words is "twenty-one billion, five hundred thirteen million, thirty-five thousand, sixty-five".