21428984 has 8 divisors (see below), whose sum is σ = 40179360. Its totient is φ = 10714488.

The previous prime is 21428971. The next prime is 21428989. The reversal of 21428984 is 48982412.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21428989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1339304 + ... + 1339319.

It is an arithmetic number, because the mean of its divisors is an integer number (5022420).

Almost surely, 2^21428984 is an apocalyptic number.

It is an amenable number.

21428984 is a deficient number, since it is larger than the sum of its proper divisors (18750376).

21428984 is a wasteful number, since it uses less digits than its factorization.

21428984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2678629 (or 2678625 counting only the distinct ones).

The product of its digits is 36864, while the sum is 38.

The square root of 21428984 is about 4629.1450614557. The cubic root of 21428984 is about 277.7583947127.

The spelling of 21428984 in words is "twenty-one million, four hundred twenty-eight thousand, nine hundred eighty-four".