21404244 has 24 divisors (see below), whose sum is σ = 50020768. Its totient is φ = 7123680.

The previous prime is 21404213. The next prime is 21404263. The reversal of 21404244 is 44240412.

It is a super-2 number, since 2×21404244² = 916283322423072, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21404244.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 11379 + ... + 13125.

Almost surely, 2^21404244 is an apocalyptic number.

It is an amenable number.

21404244 is an abundant number, since it is smaller than the sum of its proper divisors (28616524).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21404244 is a wasteful number, since it uses less digits than its factorization.

21404244 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2775 (or 2773 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 21.

The square root of 21404244 is about 4626.4720900487. The cubic root of 21404244 is about 277.6514618333.

Adding to 21404244 its reverse (44240412), we get a palindrome (65644656).

The spelling of 21404244 in words is "twenty-one million, four hundred four thousand, two hundred forty-four".