21245253 has 4 divisors (see below), whose sum is σ = 28327008. Its totient is φ = 14163500.

The previous prime is 21245227. The next prime is 21245281. The reversal of 21245253 is 35254212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21245253 - 2⁵ = 21245221 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245293) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3540873 + ... + 3540878.

It is an arithmetic number, because the mean of its divisors is an integer number (7081752).

Almost surely, 2^21245253 is an apocalyptic number.

It is an amenable number.

21245253 is a deficient number, since it is larger than the sum of its proper divisors (7081755).

21245253 is an equidigital number, since it uses as much as digits as its factorization.

21245253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7081754.

The product of its digits is 2400, while the sum is 24.

The square root of 21245253 is about 4609.2573154468. The cubic root of 21245253 is about 276.9622863937.

Adding to 21245253 its reverse (35254212), we get a palindrome (56499465).

The spelling of 21245253 in words is "twenty-one million, two hundred forty-five thousand, two hundred fifty-three".