11121991551225 has 81 divisors (see below), whose sum is σ = 20030544622413. Its totient is φ = 5899206248640.

The previous prime is 11121991551199. The next prime is 11121991551271. The reversal of 11121991551225 is 52215519912111.

The square root of 11121991551225 is 3334965.

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

11121991551225 is a `hidden beast` number, since 1 + 1 + 1 + 2 + 1 + 9 + 91 + 551 + 2 + 2 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 741326166009 + 10380665385216 = 861003^2 + 3221904^2 .

It is not a de Polignac number, because 11121991551225 - 2¹⁵ = 11121991518457 is a prime.

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

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, 11155457427 + ... + 11155458423.

Almost surely, 2^{11121991551225} is an apocalyptic number.

11121991551225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

11121991551225 is the 3334965-th square number.

11121991551225 is the 1667483-rd centered octagonal number.

It is an amenable number.

11121991551225 is a deficient number, since it is larger than the sum of its proper divisors (8908553071188).

11121991551225 is an frugal number, since it uses more digits than its factorization.

11121991551225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2456 (or 1228 counting only the distinct ones).

The product of its digits is 81000, while the sum is 45.

It can be divided in two parts, 1112199 and 1551225, that added together give a square (2663424 = 1632²).

The spelling of 11121991551225 in words is "eleven trillion, one hundred twenty-one billion, nine hundred ninety-one million, five hundred fifty-one thousand, two hundred twenty-five".