21225621 has 8 divisors (see below), whose sum is σ = 28765024. Its totient is φ = 13918320.

The previous prime is 21225613. The next prime is 21225629. The reversal of 21225621 is 12652212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21225613) and next prime (21225629).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21225621 - 2³ = 21225613 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 pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57811 + ... + 58176.

It is an arithmetic number, because the mean of its divisors is an integer number (3595628).

Almost surely, 2^21225621 is an apocalyptic number.

It is an amenable number.

21225621 is a deficient number, since it is larger than the sum of its proper divisors (7539403).

21225621 is a wasteful number, since it uses less digits than its factorization.

21225621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116051.

The product of its digits is 480, while the sum is 21.

The square root of 21225621 is about 4607.1271959867. The cubic root of 21225621 is about 276.8769496947.

Adding to 21225621 its reverse (12652212), we get a palindrome (33877833).

The spelling of 21225621 in words is "twenty-one million, two hundred twenty-five thousand, six hundred twenty-one".