11515215517 has 16 divisors (see below), whose sum is σ = 12776509872. Its totient is φ = 10309386240.

The previous prime is 11515215493. The next prime is 11515215521. The reversal of 11515215517 is 71551251511.

It can be written as a sum of positive squares in 8 ways, for example, as 361532196 + 11153683321 = 19014^2 + 105611^2 .

It is a cyclic number.

It is not a de Polignac number, because 11515215517 - 2²³ = 11506826909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11515285517) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 114717 + ... + 190237.

It is an arithmetic number, because the mean of its divisors is an integer number (798531867).

Almost surely, 2^11515215517 is an apocalyptic number.

It is an amenable number.

11515215517 is a deficient number, since it is larger than the sum of its proper divisors (1261294355).

11515215517 is a wasteful number, since it uses less digits than its factorization.

11515215517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75888.

The product of its digits is 8750, while the sum is 34.

The spelling of 11515215517 in words is "eleven billion, five hundred fifteen million, two hundred fifteen thousand, five hundred seventeen".