21423184 has 30 divisors (see below), whose sum is σ = 43818810. Its totient is φ = 10145088.

The previous prime is 21423169. The next prime is 21423221. The reversal of 21423184 is 48132412.

It can be written as a sum of positive squares in only one way, i.e., 16224784 + 5198400 = 4028^2 + 2280^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3922 + ... + 7630.

It is an arithmetic number, because the mean of its divisors is an integer number (1460627).

Almost surely, 2^21423184 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 21423184, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21909405).

21423184 is an abundant number, since it is smaller than the sum of its proper divisors (22395626).

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

21423184 is a wasteful number, since it uses less digits than its factorization.

21423184 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3755 (or 3730 counting only the distinct ones).

The product of its digits is 1536, while the sum is 25.

The square root of 21423184 is about 4628.5185534899. The cubic root of 21423184 is about 277.7333329543.

Adding to 21423184 its reverse (48132412), we get a palindrome (69555596).

The spelling of 21423184 in words is "twenty-one million, four hundred twenty-three thousand, one hundred eighty-four".