15805128645 has 30 divisors (see below), whose sum is σ = 28336692582. Its totient is φ = 8428052592.

The previous prime is 15805128623. The next prime is 15805128697. The reversal of 15805128645 is 54682150851.

15805128645 is a `hidden beast` number, since 1 + 58 + 0 + 512 + 86 + 4 + 5 = 666.

It can be written as a sum of positive squares in only one way, i.e., 12644102916 + 3161025729 = 112446^2 + 56223^2 .

It is not a de Polignac number, because 15805128645 - 2¹⁷ = 15804997573 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 15805128645.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 2526912 + ... + 2533158.

Almost surely, 2^15805128645 is an apocalyptic number.

15805128645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

15805128645 is a deficient number, since it is larger than the sum of its proper divisors (12531563937).

15805128645 is an frugal number, since it uses more digits than its factorization.

15805128645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12511 (or 6255 counting only the distinct ones).

The product of its (nonzero) digits is 384000, while the sum is 45.

Multiplying 15805128645 by its sum of digits (45), we get a square (711230789025 = 843345²).

15805128645 divided by its sum of digits (45) gives a square (351225081 = 18741²).

It can be divided in two parts, 1580 and 5128645, that added together give a square (5130225 = 2265²).

The spelling of 15805128645 in words is "fifteen billion, eight hundred five million, one hundred twenty-eight thousand, six hundred forty-five".