21184420 has 12 divisors (see below), whose sum is σ = 44487324. Its totient is φ = 8473760.

The previous prime is 21184393. The next prime is 21184441. The reversal of 21184420 is 2448112.

It can be written as a sum of positive squares in 2 ways, for example, as 11249316 + 9935104 = 3354^2 + 3152^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21184391 and 21184400.

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 3 ways as a sum of consecutive naturals, for example, 529591 + ... + 529630.

It is an arithmetic number, because the mean of its divisors is an integer number (3707277).

Almost surely, 2^21184420 is an apocalyptic number.

21184420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21184420 is an abundant number, since it is smaller than the sum of its proper divisors (23302904).

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

21184420 is a wasteful number, since it uses less digits than its factorization.

21184420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1059230 (or 1059228 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 22.

The square root of 21184420 is about 4602.6535824457. The cubic root of 21184420 is about 276.6976852692.

The spelling of 21184420 in words is "twenty-one million, one hundred eighty-four thousand, four hundred twenty".