21411221 has 8 divisors (see below), whose sum is σ = 23108064. Its totient is φ = 19721520.

The previous prime is 21411209. The next prime is 21411223. The reversal of 21411221 is 12211412.

It is a happy number.

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

It is not a de Polignac number, because 21411221 - 2²² = 17216917 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21411196 and 21411205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21411223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5606 + ... + 8616.

It is an arithmetic number, because the mean of its divisors is an integer number (2888508).

Almost surely, 2^21411221 is an apocalyptic number.

It is an amenable number.

21411221 is a deficient number, since it is larger than the sum of its proper divisors (1696843).

21411221 is a wasteful number, since it uses less digits than its factorization.

21411221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3571.

The product of its digits is 32, while the sum is 14.

The square root of 21411221 is about 4627.2260588824. The cubic root of 21411221 is about 277.6816266269.

Adding to 21411221 its reverse (12211412), we get a palindrome (33622633).

The spelling of 21411221 in words is "twenty-one million, four hundred eleven thousand, two hundred twenty-one".