21784452 has 48 divisors (see below), whose sum is σ = 53524800. Its totient is φ = 6885760.

The previous prime is 21784439. The next prime is 21784471. The reversal of 21784452 is 25448712.

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 15 ways as a sum of consecutive naturals, for example, 20002 + ... + 21062.

It is an arithmetic number, because the mean of its divisors is an integer number (1115100).

Almost surely, 2^21784452 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21784452, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26762400).

21784452 is an abundant number, since it is smaller than the sum of its proper divisors (31740348).

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

21784452 is a wasteful number, since it uses less digits than its factorization.

21784452 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1156 (or 1154 counting only the distinct ones).

The product of its digits is 17920, while the sum is 33.

The square root of 21784452 is about 4667.3817071245. The cubic root of 21784452 is about 279.2858159645.

The spelling of 21784452 in words is "twenty-one million, seven hundred eighty-four thousand, four hundred fifty-two".