18321408 has 156 divisors (see below), whose sum is σ = 61334208. Its totient is φ = 5160960.

The previous prime is 18321389. The next prime is 18321419. The reversal of 18321408 is 80412381.

It is a super-2 number, since 2×18321408² = 671347982204928, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 258013 + ... + 258083.

It is an arithmetic number, because the mean of its divisors is an integer number (393168).

Almost surely, 2^18321408 is an apocalyptic number.

18321408 is a gapful number since it is divisible by the number (18) 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 18321408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30667104).

18321408 is an abundant number, since it is smaller than the sum of its proper divisors (43012800).

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

18321408 is an equidigital number, since it uses as much as digits as its factorization.

18321408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108 (or 83 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 18321408 is about 4280.3513874447. The cubic root of 18321408 is about 263.6248113988.

Adding to 18321408 its reverse (80412381), we get a palindrome (98733789).

It can be divided in two parts, 1832 and 1408, that added together give a triangular number (3240 = T₈₀).

The spelling of 18321408 in words is "eighteen million, three hundred twenty-one thousand, four hundred eight".