15561001115 has 12 divisors (see below), whose sum is σ = 20525089872. Its totient is φ = 11317091280.

The previous prime is 15561001111. The next prime is 15561001117. The reversal of 15561001115 is 51110016551.

It is not a de Polignac number, because 15561001115 - 2² = 15561001111 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15561001111) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12859727 + ... + 12860936.

It is an arithmetic number, because the mean of its divisors is an integer number (1710424156).

Almost surely, 2^15561001115 is an apocalyptic number.

15561001115 is a deficient number, since it is larger than the sum of its proper divisors (4964088757).

15561001115 is a wasteful number, since it uses less digits than its factorization.

15561001115 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25720690 (or 25720679 counting only the distinct ones).

The product of its (nonzero) digits is 750, while the sum is 26.

Adding to 15561001115 its reverse (51110016551), we get a palindrome (66671017666).

The spelling of 15561001115 in words is "fifteen billion, five hundred sixty-one million, one thousand, one hundred fifteen".