21233421 has 20 divisors (see below), whose sum is σ = 34604064. Its totient is φ = 12868200.

The previous prime is 21233413. The next prime is 21233441. The reversal of 21233421 is 12433212.

21233421 is a `hidden beast` number, since 212 + 33 + 421 = 666.

It is not a de Polignac number, because 21233421 - 2³ = 21233413 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21233394 and 21233403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21233411) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 11025 + ... + 12806.

Almost surely, 2^21233421 is an apocalyptic number.

It is an amenable number.

21233421 is a deficient number, since it is larger than the sum of its proper divisors (13370643).

21233421 is a wasteful number, since it uses less digits than its factorization.

21233421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23854 (or 23845 counting only the distinct ones).

The product of its digits is 288, while the sum is 18.

The square root of 21233421 is about 4607.9736327371. The cubic root of 21233421 is about 276.9108611599.

Adding to 21233421 its reverse (12433212), we get a palindrome (33666633).

It can be divided in two parts, 212 and 33421, that added together give a palindrome (33633).

The spelling of 21233421 in words is "twenty-one million, two hundred thirty-three thousand, four hundred twenty-one".