21422421 has 16 divisors (see below), whose sum is σ = 31909120. Its totient is φ = 14204160.

The previous prime is 21422419. The next prime is 21422449. The reversal of 21422421 is 12422412.

It is not a de Polignac number, because 21422421 - 2¹ = 21422419 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21422394 and 21422403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21422411) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3156 + ... + 7266.

It is an arithmetic number, because the mean of its divisors is an integer number (1994320).

It is a self-describing number.

Almost surely, 2^21422421 is an apocalyptic number.

It is an amenable number.

21422421 is a deficient number, since it is larger than the sum of its proper divisors (10486699).

21422421 is a wasteful number, since it uses less digits than its factorization.

21422421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4313 (or 4307 counting only the distinct ones).

The product of its digits is 256, while the sum is 18.

The square root of 21422421 is about 4628.4361289749. The cubic root of 21422421 is about 277.7300357002.

Adding to 21422421 its reverse (12422412), we get a palindrome (33844833).

Subtracting from 21422421 its reverse (12422412), we obtain a palindrome (9000009).

The spelling of 21422421 in words is "twenty-one million, four hundred twenty-two thousand, four hundred twenty-one".