21872784 has 20 divisors (see below), whose sum is σ = 56504816. Its totient is φ = 7290912.

The previous prime is 21872783. The next prime is 21872789. The reversal of 21872784 is 48727812.

It is not an unprimeable number, because it can be changed into a prime (21872783) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 227794 + ... + 227889.

Almost surely, 2^21872784 is an apocalyptic number.

21872784 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21872784 is an abundant number, since it is smaller than the sum of its proper divisors (34632032).

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

21872784 is a wasteful number, since it uses less digits than its factorization.

21872784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 455694 (or 455688 counting only the distinct ones).

The product of its digits is 50176, while the sum is 39.

The square root of 21872784 is about 4676.8348271026. The cubic root of 21872784 is about 279.6627913359.

The spelling of 21872784 in words is "twenty-one million, eight hundred seventy-two thousand, seven hundred eighty-four".