21334431 has 4 divisors (see below), whose sum is σ = 28445912. Its totient is φ = 14222952.

The previous prime is 21334427. The next prime is 21334433. The reversal of 21334431 is 13443312.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21334431 - 2² = 21334427 is a prime.

It is a super-2 number, since 2×21334431² = 910315892187522, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 21334398 and 21334407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21334433) 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, 3555736 + ... + 3555741.

It is an arithmetic number, because the mean of its divisors is an integer number (7111478).

Almost surely, 2^21334431 is an apocalyptic number.

21334431 is a deficient number, since it is larger than the sum of its proper divisors (7111481).

21334431 is an equidigital number, since it uses as much as digits as its factorization.

21334431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7111480.

The product of its digits is 864, while the sum is 21.

The square root of 21334431 is about 4618.9209778908. The cubic root of 21334431 is about 277.3492664059.

Adding to 21334431 its reverse (13443312), we get a palindrome (34777743).

The spelling of 21334431 in words is "twenty-one million, three hundred thirty-four thousand, four hundred thirty-one".