21842784 has 108 divisors (see below), whose sum is σ = 65654316. Its totient is φ = 7143552.

The previous prime is 21842767. The next prime is 21842797. The reversal of 21842784 is 48724812.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It is a tau number, because it is divible by the number of its divisors (108).

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

It is a congruent number.

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 17 ways as a sum of consecutive naturals, for example, 412102 + ... + 412154.

Almost surely, 2^21842784 is an apocalyptic number.

21842784 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21842784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32827158).

21842784 is an abundant number, since it is smaller than the sum of its proper divisors (43811532).

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

21842784 is an frugal number, since it uses more digits than its factorization.

21842784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131 (or 58 counting only the distinct ones).

The product of its digits is 28672, while the sum is 36.

The square root of 21842784 is about 4673.6264292303. The cubic root of 21842784 is about 279.5348740358.

The spelling of 21842784 in words is "twenty-one million, eight hundred forty-two thousand, seven hundred eighty-four".