21807905625 has 135 divisors (see below), whose sum is σ = 43509595129. Its totient is φ = 10514460000.

The previous prime is 21807905611. The next prime is 21807905629. The reversal of 21807905625 is 52650970812.

The square root of 21807905625 is 147675.

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

21807905625 is a `hidden beast` number, since 2 + 1 + 80 + 7 + 9 + 0 + 562 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1709739801 + 20098165824 = 41349^2 + 141768^2 .

It is not a de Polignac number, because 21807905625 - 2¹¹ = 21807903577 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (21807905629) 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 134 ways as a sum of consecutive naturals, for example, 121831786 + ... + 121831964.

Almost surely, 2^21807905625 is an apocalyptic number.

21807905625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21807905625 is the 147675-th square number.

21807905625 is the 73838-th centered octagonal number.

It is an amenable number.

21807905625 is a deficient number, since it is larger than the sum of its proper divisors (21701689504).

21807905625 is an equidigital number, since it uses as much as digits as its factorization.

21807905625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 406 (or 198 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The spelling of 21807905625 in words is "twenty-one billion, eight hundred seven million, nine hundred five thousand, six hundred twenty-five".