1866543426225 has 27 divisors (see below), whose sum is σ = 3343223376129. Its totient is φ = 995478897600.

The previous prime is 1866543426197. The next prime is 1866543426233. The reversal of 1866543426225 is 5226243456681.

The square root of 1866543426225 is 1366215.

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

1866543426225 is a `hidden beast` number, since 1 + 8 + 6 + 6 + 5 + 4 + 3 + 4 + 2 + 622 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 21260264481 + 1845283161744 = 145809^2 + 1358412^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1866543426225 is a prime.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 20447685 + ... + 20538765.

Almost surely, 2^{1866543426225} is an apocalyptic number.

1866543426225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1866543426225 is the 1366215-th square number.

1866543426225 is the 683108-th centered octagonal number.

It is an amenable number.

1866543426225 is a deficient number, since it is larger than the sum of its proper divisors (1476679949904).

1866543426225 is an frugal number, since it uses more digits than its factorization.

1866543426225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182178 (or 91089 counting only the distinct ones).

The product of its digits is 16588800, while the sum is 54.

The spelling of 1866543426225 in words is "one trillion, eight hundred sixty-six billion, five hundred forty-three million, four hundred twenty-six thousand, two hundred twenty-five".