21283421 has 4 divisors (see below), whose sum is σ = 21601152. Its totient is φ = 20965692.

The previous prime is 21283417. The next prime is 21283447. The reversal of 21283421 is 12438212.

It is a happy number.

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 21283421 - 2² = 21283417 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 (21283411) 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 3 ways as a sum of consecutive naturals, for example, 158765 + ... + 158898.

It is an arithmetic number, because the mean of its divisors is an integer number (5400288).

Almost surely, 2^21283421 is an apocalyptic number.

It is an amenable number.

21283421 is a deficient number, since it is larger than the sum of its proper divisors (317731).

21283421 is an equidigital number, since it uses as much as digits as its factorization.

21283421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317730.

The product of its digits is 768, while the sum is 23.

The square root of 21283421 is about 4613.3958208677. The cubic root of 21283421 is about 277.1280453420.

The spelling of 21283421 in words is "twenty-one million, two hundred eighty-three thousand, four hundred twenty-one".