18219820 has 24 divisors (see below), whose sum is σ = 38342304. Its totient is φ = 7272576.

The previous prime is 18219809. The next prime is 18219821. The reversal of 18219820 is 2891281.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (18219821) 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, 16609 + ... + 17671.

It is an arithmetic number, because the mean of its divisors is an integer number (1597596).

Almost surely, 2^18219820 is an apocalyptic number.

18219820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18219820 is an abundant number, since it is smaller than the sum of its proper divisors (20122484).

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

18219820 is a wasteful number, since it uses less digits than its factorization.

18219820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1929 (or 1927 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 18219820 is about 4268.4681092870. The cubic root of 18219820 is about 263.1366617114.

It can be divided in two parts, 182 and 19820, that added together give a palindrome (20002).

The spelling of 18219820 in words is "eighteen million, two hundred nineteen thousand, eight hundred twenty".