21441221 has 4 divisors (see below), whose sum is σ = 22373472. Its totient is φ = 20508972.

The previous prime is 21441197. The next prime is 21441223. The reversal of 21441221 is 12214412.

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 21441221 - 2²² = 17246917 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21441221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21441223) 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, 466091 + ... + 466136.

It is an arithmetic number, because the mean of its divisors is an integer number (5593368).

Almost surely, 2^21441221 is an apocalyptic number.

It is an amenable number.

21441221 is a deficient number, since it is larger than the sum of its proper divisors (932251).

21441221 is an equidigital number, since it uses as much as digits as its factorization.

21441221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 932250.

The product of its digits is 128, while the sum is 17.

The square root of 21441221 is about 4630.4666071574. The cubic root of 21441221 is about 277.8112558702.

Adding to 21441221 its reverse (12214412), we get a palindrome (33655633).

The spelling of 21441221 in words is "twenty-one million, four hundred forty-one thousand, two hundred twenty-one".