15779128225 has 81 divisors (see below), whose sum is σ = 23636008683. Its totient is φ = 10419010560.

The previous prime is 15779128207. The next prime is 15779128231. The reversal of 15779128225 is 52282197751.

The square root of 15779128225 is 125615.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 13 ways, for example, as 3939947361 + 11839180864 = 62769^2 + 108808^2 .

It is not a de Polignac number, because 15779128225 - 2¹¹ = 15779126177 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is an unprimeable number.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 162671377 + ... + 162671473.

Almost surely, 2^15779128225 is an apocalyptic number.

15779128225 is the 125615-th square number.

15779128225 is the 62808-th centered octagonal number.

It is an amenable number.

15779128225 is a deficient number, since it is larger than the sum of its proper divisors (7856880458).

15779128225 is an frugal number, since it uses more digits than its factorization.

15779128225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292 (or 146 counting only the distinct ones).

The product of its digits is 705600, while the sum is 49.

Multiplying 15779128225 by its sum of digits (49), we get a square (773177283025 = 879305²).

15779128225 divided by its sum of digits (49) gives a square (322023025 = 17945²).

The spelling of 15779128225 in words is "fifteen billion, seven hundred seventy-nine million, one hundred twenty-eight thousand, two hundred twenty-five".