21026253 has 4 divisors (see below), whose sum is σ = 28035008. Its totient is φ = 14017500.

The previous prime is 21026251. The next prime is 21026267. The reversal of 21026253 is 35262012.

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 not a de Polignac number, because 21026253 - 2¹ = 21026251 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 (21026251) 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, 3504373 + ... + 3504378.

It is an arithmetic number, because the mean of its divisors is an integer number (7008752).

Almost surely, 2^21026253 is an apocalyptic number.

It is an amenable number.

21026253 is a deficient number, since it is larger than the sum of its proper divisors (7008755).

21026253 is an equidigital number, since it uses as much as digits as its factorization.

21026253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7008754.

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 21026253 is about 4585.4392374123. The cubic root of 21026253 is about 276.0073380742.

Adding to 21026253 its reverse (35262012), we get a palindrome (56288265).

The spelling of 21026253 in words is "twenty-one million, twenty-six thousand, two hundred fifty-three".