21428744 has 16 divisors (see below), whose sum is σ = 40779600. Its totient is φ = 10554192.

The previous prime is 21428731. The next prime is 21428747. The reversal of 21428744 is 44782412.

It is a self number, because there is not a number n which added to its sum of digits gives 21428744.

It is not an unprimeable number, because it can be changed into a prime (21428747) by changing a digit.

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, 19454 + ... + 20525.

It is an arithmetic number, because the mean of its divisors is an integer number (2548725).

Almost surely, 2^21428744 is an apocalyptic number.

It is an amenable number.

21428744 is a deficient number, since it is larger than the sum of its proper divisors (19350856).

21428744 is a wasteful number, since it uses less digits than its factorization.

21428744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40052 (or 40048 counting only the distinct ones).

The product of its digits is 14336, while the sum is 32.

The square root of 21428744 is about 4629.1191386699. The cubic root of 21428744 is about 277.7573577641.

The spelling of 21428744 in words is "twenty-one million, four hundred twenty-eight thousand, seven hundred forty-four".