21118284 has 72 divisors (see below), whose sum is σ = 61680528. Its totient is φ = 6021120.

The previous prime is 21118277. The next prime is 21118303. The reversal of 21118284 is 48281112.

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 23 ways as a sum of consecutive naturals, for example, 5164 + ... + 8300.

It is an arithmetic number, because the mean of its divisors is an integer number (856674).

Almost surely, 2^21118284 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 21118284, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30840264).

21118284 is an abundant number, since it is smaller than the sum of its proper divisors (40562244).

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

21118284 is a wasteful number, since it uses less digits than its factorization.

21118284 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3175 (or 3170 counting only the distinct ones).

The product of its digits is 1024, while the sum is 27.

The square root of 21118284 is about 4595.4634151519. The cubic root of 21118284 is about 276.4094427059.

Adding to 21118284 its reverse (48281112), we get a palindrome (69399396).

The spelling of 21118284 in words is "twenty-one million, one hundred eighteen thousand, two hundred eighty-four".