21044404 has 6 divisors (see below), whose sum is σ = 36827714. Its totient is φ = 10522200.

The previous prime is 21044399. The next prime is 21044407. The reversal of 21044404 is 40444012.

It can be written as a sum of positive squares in only one way, i.e., 18147600 + 2896804 = 4260^2 + 1702^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21044407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2630547 + ... + 2630554.

Almost surely, 2^21044404 is an apocalyptic number.

It is an amenable number.

21044404 is a deficient number, since it is larger than the sum of its proper divisors (15783310).

21044404 is a wasteful number, since it uses less digits than its factorization.

21044404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5261105 (or 5261103 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 19.

The square root of 21044404 is about 4587.4180101665. The cubic root of 21044404 is about 276.0867367241.

Adding to 21044404 its reverse (40444012), we get a palindrome (61488416).

The spelling of 21044404 in words is "twenty-one million, forty-four thousand, four hundred four".