18421938 has 32 divisors (see below), whose sum is σ = 41313600. Its totient is φ = 6084288.

The previous prime is 18421891. The next prime is 18421943. The reversal of 18421938 is 83912481.

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, 4593 + ... + 7611.

It is an arithmetic number, because the mean of its divisors is an integer number (1291050).

Almost surely, 2^18421938 is an apocalyptic number.

18421938 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 18421938, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20656800).

18421938 is an abundant number, since it is smaller than the sum of its proper divisors (22891662).

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

18421938 is a wasteful number, since it uses less digits than its factorization.

18421938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3143 (or 3137 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 18421938 is about 4292.0785174552. The cubic root of 18421938 is about 264.1061040443.

It can be divided in two parts, 184 and 21938, that added together give a palindrome (22122).

The spelling of 18421938 in words is "eighteen million, four hundred twenty-one thousand, nine hundred thirty-eight".