21450253 has 4 divisors (see below), whose sum is σ = 23400288. Its totient is φ = 19500220.

The previous prime is 21450241. The next prime is 21450293. The reversal of 21450253 is 35205412.

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 21450253 - 2⁹ = 21449741 is a prime.

It is a super-2 number, since 2×21450253² = 920226707528018, which contains 22 as substring.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21450293) 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, 975001 + ... + 975022.

It is an arithmetic number, because the mean of its divisors is an integer number (5850072).

Almost surely, 2^21450253 is an apocalyptic number.

It is an amenable number.

21450253 is a deficient number, since it is larger than the sum of its proper divisors (1950035).

21450253 is a wasteful number, since it uses less digits than its factorization.

21450253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1950034.

The product of its (nonzero) digits is 1200, while the sum is 22.

The square root of 21450253 is about 4631.4417841532. The cubic root of 21450253 is about 277.8502592307.

Adding to 21450253 its reverse (35205412), we get a palindrome (56655665).

The spelling of 21450253 in words is "twenty-one million, four hundred fifty thousand, two hundred fifty-three".