18221420 has 48 divisors (see below), whose sum is σ = 44063040. Its totient is φ = 6200064.

The previous prime is 18221417. The next prime is 18221431. The reversal of 18221420 is 2412281.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 18221392 and 18221401.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21566 + ... + 22394.

It is an arithmetic number, because the mean of its divisors is an integer number (917980).

Almost surely, 2^18221420 is an apocalyptic number.

18221420 is a gapful number since it is divisible by the number (10) 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 18221420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22031520).

18221420 is an abundant number, since it is smaller than the sum of its proper divisors (25841620).

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

18221420 is a wasteful number, since it uses less digits than its factorization.

18221420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1002 (or 1000 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 18221420 is about 4268.6555260410. The cubic root of 18221420 is about 263.1443640622.

The spelling of 18221420 in words is "eighteen million, two hundred twenty-one thousand, four hundred twenty".