15818636880225 has 27 divisors (see below), whose sum is σ = 28333043135059. Its totient is φ = 8436574518000.

The previous prime is 15818636880191. The next prime is 15818636880229. The reversal of 15818636880225 is 52208863681851.

It is a happy number.

The square root of 15818636880225 is 3977265.

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

15818636880225 is a `hidden beast` number, since 15 + 8 + 186 + 368 + 80 + 2 + 2 + 5 = 666.

It can be written as a sum of positive squares in only one way, i.e., 5694709276881 + 10123927603344 = 2386359^2 + 3181812^2 .

It is a de Polignac number, because none of the positive numbers 2^k-15818636880225 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15818636880229) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 59526400 + ... + 59791550.

Almost surely, 2^{15818636880225} is an apocalyptic number.

15818636880225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

15818636880225 is the 3977265-th square number.

15818636880225 is the 1988633-rd centered octagonal number.

It is an amenable number.

15818636880225 is a deficient number, since it is larger than the sum of its proper divisors (12514406254834).

15818636880225 is an frugal number, since it uses more digits than its factorization.

15818636880225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 530318 (or 265159 counting only the distinct ones).

The product of its (nonzero) digits is 44236800, while the sum is 63.

The spelling of 15818636880225 in words is "fifteen trillion, eight hundred eighteen billion, six hundred thirty-six million, eight hundred eighty thousand, two hundred twenty-five".