21328218 has 16 divisors (see below), whose sum is σ = 47396160. Its totient is φ = 7109388.

The previous prime is 21328213. The next prime is 21328247. The reversal of 21328218 is 81282312.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21328191 and 21328200.

It is not an unprimeable number, because it can be changed into a prime (21328213) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 197430 + ... + 197537.

It is an arithmetic number, because the mean of its divisors is an integer number (2962260).

Almost surely, 2^21328218 is an apocalyptic number.

21328218 is an abundant number, since it is smaller than the sum of its proper divisors (26067942).

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

21328218 is a wasteful number, since it uses less digits than its factorization.

21328218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394978 (or 394972 counting only the distinct ones).

The product of its digits is 1536, while the sum is 27.

The square root of 21328218 is about 4618.2483692413. The cubic root of 21328218 is about 277.3223406305.

The spelling of 21328218 in words is "twenty-one million, three hundred twenty-eight thousand, two hundred eighteen".