21225421 has 8 divisors (see below), whose sum is σ = 25040384. Its totient is φ = 17606160.

The previous prime is 21225403. The next prime is 21225431. The reversal of 21225421 is 12452212.

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

It is a cyclic number.

It is not a de Polignac number, because 21225421 - 2⁷ = 21225293 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 (21225431) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48690 + ... + 49123.

It is an arithmetic number, because the mean of its divisors is an integer number (3130048).

Almost surely, 2^21225421 is an apocalyptic number.

It is an amenable number.

21225421 is a deficient number, since it is larger than the sum of its proper divisors (3814963).

21225421 is an equidigital number, since it uses as much as digits as its factorization.

21225421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97851.

The product of its digits is 320, while the sum is 19.

The square root of 21225421 is about 4607.1054904354. The cubic root of 21225421 is about 276.8760800607.

Adding to 21225421 its reverse (12452212), we get a palindrome (33677633).

The spelling of 21225421 in words is "twenty-one million, two hundred twenty-five thousand, four hundred twenty-one".