11615636721 has 32 divisors (see below), whose sum is σ = 17074737792. Its totient is φ = 6979714560.

The previous prime is 11615636717. The next prime is 11615636743. The reversal of 11615636721 is 12763651611.

It is not a de Polignac number, because 11615636721 - 2² = 11615636717 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a self number, because there is not a number n which added to its sum of digits gives 11615636721.

It is not an unprimeable number, because it can be changed into a prime (11615636321) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 422821 + ... + 449453.

It is an arithmetic number, because the mean of its divisors is an integer number (533585556).

Almost surely, 2^11615636721 is an apocalyptic number.

It is an amenable number.

11615636721 is a deficient number, since it is larger than the sum of its proper divisors (5459101071).

11615636721 is a wasteful number, since it uses less digits than its factorization.

11615636721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26913.

The product of its digits is 45360, while the sum is 39.

The spelling of 11615636721 in words is "eleven billion, six hundred fifteen million, six hundred thirty-six thousand, seven hundred twenty-one".