2161812825 has 18 divisors (see below), whose sum is σ = 3872047374. Its totient is φ = 1152966720.

The previous prime is 2161812823. The next prime is 2161812833. The reversal of 2161812825 is 5282181612.

2161812825 is a `hidden beast` number, since 2 + 1 + 618 + 12 + 8 + 25 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 481714704 + 1680098121 = 21948^2 + 40989^2 .

It is not a de Polignac number, because 2161812825 - 2¹ = 2161812823 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2161812825.

It is not an unprimeable number, because it can be changed into a prime (2161812823) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 4803804 + ... + 4804253.

It is an arithmetic number, because the mean of its divisors is an integer number (215113743).

Almost surely, 2^2161812825 is an apocalyptic number.

2161812825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

2161812825 is a deficient number, since it is larger than the sum of its proper divisors (1710234549).

2161812825 is a wasteful number, since it uses less digits than its factorization.

2161812825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9608073 (or 9608065 counting only the distinct ones).

The product of its digits is 15360, while the sum is 36.

The square root of 2161812825 is about 46495.2989559160. The cubic root of 2161812825 is about 1293.0223437371.

It can be divided in two parts, 21618 and 12825, that added together give a palindrome (34443).

The spelling of 2161812825 in words is "two billion, one hundred sixty-one million, eight hundred twelve thousand, eight hundred twenty-five".