21322421 has 4 divisors (see below), whose sum is σ = 21332832. Its totient is φ = 21312012.

The previous prime is 21322417. The next prime is 21322439. The reversal of 21322421 is 12422312.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21322421 - 2² = 21322417 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21322421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21322481) 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 3 ways as a sum of consecutive naturals, for example, 1001 + ... + 6606.

It is an arithmetic number, because the mean of its divisors is an integer number (5333208).

Almost surely, 2^21322421 is an apocalyptic number.

It is an amenable number.

21322421 is a deficient number, since it is larger than the sum of its proper divisors (10411).

21322421 is an equidigital number, since it uses as much as digits as its factorization.

21322421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10410.

The product of its digits is 192, while the sum is 17.

The square root of 21322421 is about 4617.6207076805. The cubic root of 21322421 is about 277.2972129916.

Adding to 21322421 its reverse (12422312), we get a palindrome (33744733).

The spelling of 21322421 in words is "twenty-one million, three hundred twenty-two thousand, four hundred twenty-one".