21418384 has 45 divisors (see below), whose sum is σ = 45446403. Its totient is φ = 9774336.

The previous prime is 21418379. The next prime is 21418403. The reversal of 21418384 is 48381412.

The square root of 21418384 is 4628.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 9363600 + 12054784 = 3060^2 + 3472^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 240612 + ... + 240700.

Almost surely, 2^21418384 is an apocalyptic number.

21418384 is the 4628-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21418384

21418384 is an abundant number, since it is smaller than the sum of its proper divisors (24028019).

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

21418384 is an equidigital number, since it uses as much as digits as its factorization.

21418384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212 (or 104 counting only the distinct ones).

The product of its digits is 6144, while the sum is 31.

The cubic root of 21418384 is about 277.7125887678.

Adding to 21418384 its reverse (48381412), we get a palindrome (69799796).

The spelling of 21418384 in words is "twenty-one million, four hundred eighteen thousand, three hundred eighty-four".