18855409225 has 27 divisors (see below), whose sum is σ = 24240336757. Its totient is φ = 14548798880.

The previous prime is 18855409163. The next prime is 18855409229. The reversal of 18855409225 is 52290455881.

The square root of 18855409225 is 137315.

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

It can be written as a sum of positive squares in 4 ways, for example, as 259177801 + 18596231424 = 16099^2 + 136368^2 .

It is not a de Polignac number, because 18855409225 - 2¹⁵ = 18855376457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18855409229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 19910202 + ... + 19911148.

Almost surely, 2^18855409225 is an apocalyptic number.

18855409225 is the 137315-th square number.

18855409225 is the 68658-th centered octagonal number.

It is an amenable number.

18855409225 is a deficient number, since it is larger than the sum of its proper divisors (5384927532).

18855409225 is an frugal number, since it uses more digits than its factorization.

18855409225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1962 (or 981 counting only the distinct ones).

The product of its (nonzero) digits is 1152000, while the sum is 49.

Multiplying 18855409225 by its sum of digits (49), we get a square (923915052025 = 961205²).

The spelling of 18855409225 in words is "eighteen billion, eight hundred fifty-five million, four hundred nine thousand, two hundred twenty-five".