21280044 has 12 divisors (see below), whose sum is σ = 49653464. Its totient is φ = 7093344.

The previous prime is 21280013. The next prime is 21280067. The reversal of 21280044 is 44008212.

It is a tau number, because it is divible by the number of its divisors (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21280044.

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 3 ways as a sum of consecutive naturals, for example, 886657 + ... + 886680.

Almost surely, 2^21280044 is an apocalyptic number.

It is an amenable number.

21280044 is an abundant number, since it is smaller than the sum of its proper divisors (28373420).

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

21280044 is a wasteful number, since it uses less digits than its factorization.

21280044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1773344 (or 1773342 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 21.

The square root of 21280044 is about 4613.0298069707. The cubic root of 21280044 is about 277.1133874398.

Adding to 21280044 its reverse (44008212), we get a palindrome (65288256).

The spelling of 21280044 in words is "twenty-one million, two hundred eighty thousand, forty-four".