21225623 has 4 divisors (see below), whose sum is σ = 21677280. Its totient is φ = 20773968.

The previous prime is 21225613. The next prime is 21225629. The reversal of 21225623 is 32652212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21225623 - 2⁶ = 21225559 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 (21225629) 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, 225758 + ... + 225851.

It is an arithmetic number, because the mean of its divisors is an integer number (5419320).

Almost surely, 2^21225623 is an apocalyptic number.

21225623 is a deficient number, since it is larger than the sum of its proper divisors (451657).

21225623 is an equidigital number, since it uses as much as digits as its factorization.

21225623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451656.

The product of its digits is 1440, while the sum is 23.

The square root of 21225623 is about 4607.1274130417. The cubic root of 21225623 is about 276.8769583910.

Adding to 21225623 its reverse (32652212), we get a palindrome (53877835).

The spelling of 21225623 in words is "twenty-one million, two hundred twenty-five thousand, six hundred twenty-three".