21036253 has 4 divisors (see below), whose sum is σ = 24041440. Its totient is φ = 18031068.

The previous prime is 21036241. The next prime is 21036269. The reversal of 21036253 is 35263012.

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 a de Polignac number, because none of the positive numbers 2^k-21036253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21036203) 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, 1502583 + ... + 1502596.

It is an arithmetic number, because the mean of its divisors is an integer number (6010360).

Almost surely, 2^21036253 is an apocalyptic number.

It is an amenable number.

21036253 is a deficient number, since it is larger than the sum of its proper divisors (3005187).

21036253 is an equidigital number, since it uses as much as digits as its factorization.

21036253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3005186.

The product of its (nonzero) digits is 1080, while the sum is 22.

The square root of 21036253 is about 4586.5295158758. The cubic root of 21036253 is about 276.0510871266.

Adding to 21036253 its reverse (35263012), we get a palindrome (56299265).

It can be divided in two parts, 210 and 36253, that added together give a palindrome (36463).

The spelling of 21036253 in words is "twenty-one million, thirty-six thousand, two hundred fifty-three".