21406433 has 4 divisors (see below), whose sum is σ = 21726000. Its totient is φ = 21086868.

The previous prime is 21406397. The next prime is 21406457. The reversal of 21406433 is 33460412.

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 21406433 - 2¹⁰ = 21405409 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21406399 and 21406408.

It is not an unprimeable number, because it can be changed into a prime (21406493) 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, 159683 + ... + 159816.

It is an arithmetic number, because the mean of its divisors is an integer number (5431500).

Almost surely, 2^21406433 is an apocalyptic number.

It is an amenable number.

21406433 is a deficient number, since it is larger than the sum of its proper divisors (319567).

21406433 is an equidigital number, since it uses as much as digits as its factorization.

21406433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319566.

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 21406433 is about 4626.7086573503. The cubic root of 21406433 is about 277.6609265970.

Adding to 21406433 its reverse (33460412), we get a palindrome (54866845).

The spelling of 21406433 in words is "twenty-one million, four hundred six thousand, four hundred thirty-three".