21118320 has 100 divisors (see below), whose sum is σ = 73369560. Its totient is φ = 5629824.

The previous prime is 21118303. The next prime is 21118337. The reversal of 21118320 is 2381112.

It is an interprime number because it is at equal distance from previous prime (21118303) and next prime (21118337).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21118293 and 21118302.

It is a congruent number.

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 19 ways as a sum of consecutive naturals, for example, 4851 + ... + 8109.

Almost surely, 2^21118320 is an apocalyptic number.

21118320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21118320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36684780).

21118320 is an abundant number, since it is smaller than the sum of its proper divisors (52251240).

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

21118320 is a wasteful number, since it uses less digits than its factorization.

21118320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3284 (or 3269 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21118320 is about 4595.4673320567. The cubic root of 21118320 is about 276.4095997693.

Adding to 21118320 its reverse (2381112), we get a palindrome (23499432).

It can be divided in two parts, 21 and 118320, that added together give a triangular number (118341 = T₄₈₆).

The spelling of 21118320 in words is "twenty-one million, one hundred eighteen thousand, three hundred twenty".