18220840 has 32 divisors (see below), whose sum is σ = 44724960. Its totient is φ = 6625600.

The previous prime is 18220823. The next prime is 18220841. The reversal of 18220840 is 4802281.

It is not an unprimeable number, because it can be changed into a prime (18220841) 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, 20266 + ... + 21145.

It is an arithmetic number, because the mean of its divisors is an integer number (1397655).

Almost surely, 2^18220840 is an apocalyptic number.

18220840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18220840 is an abundant number, since it is smaller than the sum of its proper divisors (26504120).

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

18220840 is a wasteful number, since it uses less digits than its factorization.

18220840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41433 (or 41429 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 25.

The square root of 18220840 is about 4268.5875884184. The cubic root of 18220840 is about 263.1415720121.

The spelling of 18220840 in words is "eighteen million, two hundred twenty thousand, eight hundred forty".