21284856 has 48 divisors (see below), whose sum is σ = 59787000. Its totient is φ = 7094304.

The previous prime is 21284839. The next prime is 21284903. The reversal of 21284856 is 65848212.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21284856.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3531 + ... + 7418.

Almost surely, 2^21284856 is an apocalyptic number.

It is an amenable number.

21284856 is an abundant number, since it is smaller than the sum of its proper divisors (38502144).

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

21284856 is a wasteful number, since it uses less digits than its factorization.

21284856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10970 (or 10954 counting only the distinct ones).

The product of its digits is 30720, while the sum is 36.

The square root of 21284856 is about 4613.5513435964. The cubic root of 21284856 is about 277.1342735045.

The spelling of 21284856 in words is "twenty-one million, two hundred eighty-four thousand, eight hundred fifty-six".