21223253 has 4 divisors (see below), whose sum is σ = 21429408. Its totient is φ = 21017100.

The previous prime is 21223219. The next prime is 21223261. The reversal of 21223253 is 35232212.

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 21223253 - 2²⁴ = 4446037 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 (21223283) 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, 102923 + ... + 103128.

It is an arithmetic number, because the mean of its divisors is an integer number (5357352).

Almost surely, 2^21223253 is an apocalyptic number.

It is an amenable number.

21223253 is a deficient number, since it is larger than the sum of its proper divisors (206155).

21223253 is a wasteful number, since it uses less digits than its factorization.

21223253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206154.

The product of its digits is 720, while the sum is 20.

The square root of 21223253 is about 4606.8701956969. The cubic root of 21223253 is about 276.8666528778.

Adding to 21223253 its reverse (35232212), we get a palindrome (56455465).

The spelling of 21223253 in words is "twenty-one million, two hundred twenty-three thousand, two hundred fifty-three".