21044431 has 2 divisors, whose sum is σ = 21044432. Its totient is φ = 21044430.

The previous prime is 21044423. The next prime is 21044467. The reversal of 21044431 is 13444012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21044431 - 2³ = 21044423 is a prime.

It is a super-2 number, since 2×21044431² = 885736152227522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21044399 and 21044408.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21044531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10522215 + 10522216.

It is an arithmetic number, because the mean of its divisors is an integer number (10522216).

Almost surely, 2^21044431 is an apocalyptic number.

21044431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21044431 is an equidigital number, since it uses as much as digits as its factorization.

21044431 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 21044431 is about 4587.4209529974. The cubic root of 21044431 is about 276.0868547973.

Adding to 21044431 its reverse (13444012), we get a palindrome (34488443).

The spelling of 21044431 in words is "twenty-one million, forty-four thousand, four hundred thirty-one".