21252500 has 30 divisors (see below), whose sum is σ = 46480434. Its totient is φ = 8500000.

The previous prime is 21252487. The next prime is 21252503. The reversal of 21252500 is 525212.

It can be written as a sum of positive squares in 5 ways, for example, as 13512976 + 7739524 = 3676^2 + 2782^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252503) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1751 + ... + 6750.

Almost surely, 2^21252500 is an apocalyptic number.

21252500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21252500 is an abundant number, since it is smaller than the sum of its proper divisors (25227934).

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

21252500 is an equidigital number, since it uses as much as digits as its factorization.

21252500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8525 (or 8508 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 21252500 is about 4610.0433837438. The cubic root of 21252500 is about 276.9937744868.

Adding to 21252500 its reverse (525212), we get a palindrome (21777712).

The spelling of 21252500 in words is "twenty-one million, two hundred fifty-two thousand, five hundred".