15561001116 has 72 divisors (see below), whose sum is σ = 40032894720. Its totient is φ = 5095370016.

The previous prime is 15561001111. The next prime is 15561001117. The reversal of 15561001116 is 61110016551.

15561001116 is a `hidden beast` number, since 1 + 556 + 100 + 1 + 1 + 1 + 6 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 15561001116.

It is a congruent 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 23 ways as a sum of consecutive naturals, for example, 876415 + ... + 893993.

Almost surely, 2^15561001116 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 15561001116, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20016447360).

15561001116 is an abundant number, since it is smaller than the sum of its proper divisors (24471893604).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

15561001116 is a wasteful number, since it uses less digits than its factorization.

15561001116 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18023 (or 18018 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 27.

Adding to 15561001116 its reverse (61110016551), we get a palindrome (76671017667).

The spelling of 15561001116 in words is "fifteen billion, five hundred sixty-one million, one thousand, one hundred sixteen".