18220400 has 120 divisors (see below), whose sum is σ = 49403088. Its totient is φ = 6400000.

The previous prime is 18220387. The next prime is 18220403. The reversal of 18220400 is 402281.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18220403) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 180350 + ... + 180450.

Almost surely, 2^18220400 is an apocalyptic number.

18220400 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 18220400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24701544).

18220400 is an abundant number, since it is smaller than the sum of its proper divisors (31182688).

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

18220400 is a wasteful number, since it uses less digits than its factorization.

18220400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171 (or 160 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 18220400 is about 4268.5360488111. The cubic root of 18220400 is about 263.1394538657.

Adding to 18220400 its reverse (402281), we get a palindrome (18622681).

The spelling of 18220400 in words is "eighteen million, two hundred twenty thousand, four hundred".