21393450225 has 135 divisors (see below), whose sum is σ = 44927488203. Its totient is φ = 9730717920.

The previous prime is 21393450187. The next prime is 21393450259. The reversal of 21393450225 is 52205439312.

The square root of 21393450225 is 146265.

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

21393450225 is a `hidden beast` number, since 2 + 1 + 393 + 45 + 0 + 225 = 666.

It can be written as a sum of positive squares in only one way, i.e., 7701642081 + 13691808144 = 87759^2 + 117012^2 .

It is not a de Polignac number, because 21393450225 - 2¹¹ = 21393448177 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21393450225.

It is an unprimeable number.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 107504676 + ... + 107504874.

Almost surely, 2^21393450225 is an apocalyptic number.

21393450225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21393450225 is the 146265-th square number.

21393450225 is the 73133-rd centered octagonal number.

It is an amenable number.

21393450225 is an abundant number, since it is smaller than the sum of its proper divisors (23534037978).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21393450225 is an frugal number, since it uses more digits than its factorization.

21393450225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442 (or 214 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

Multiplying 21393450225 by its sum of digits (36), we get a square (770164208100 = 877590²).

Adding to 21393450225 its reverse (52205439312), we get a palindrome (73598889537).

The spelling of 21393450225 in words is "twenty-one billion, three hundred ninety-three million, four hundred fifty thousand, two hundred twenty-five".