21841218 has 32 divisors (see below), whose sum is σ = 55470720. Its totient is φ = 6240240.

The previous prime is 21841217. The next prime is 21841273. The reversal of 21841218 is 81214812.

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 = 21841191 and 21841200.

It is not an unprimeable number, because it can be changed into a prime (21841217) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28513 + ... + 29268.

It is an arithmetic number, because the mean of its divisors is an integer number (1733460).

Almost surely, 2^21841218 is an apocalyptic number.

21841218 is an abundant number, since it is smaller than the sum of its proper divisors (33629502).

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

21841218 is a wasteful number, since it uses less digits than its factorization.

21841218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57799 (or 57793 counting only the distinct ones).

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

The square root of 21841218 is about 4673.4588903723. The cubic root of 21841218 is about 279.5281935370.

The spelling of 21841218 in words is "twenty-one million, eight hundred forty-one thousand, two hundred eighteen".