18421380 has 72 divisors (see below), whose sum is σ = 57821400. Its totient is φ = 4741632.

The previous prime is 18421379. The next prime is 18421399. The reversal of 18421380 is 8312481.

It can be written as a sum of positive squares in 4 ways, for example, as 171396 + 18249984 = 414^2 + 4272^2 .

It is a super-2 number, since 2×18421380² = 678694482208800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3456 + ... + 6984.

It is an arithmetic number, because the mean of its divisors is an integer number (803075).

Almost surely, 2^18421380 is an apocalyptic number.

18421380 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 18421380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28910700).

18421380 is an abundant number, since it is smaller than the sum of its proper divisors (39400020).

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

18421380 is a wasteful number, since it uses less digits than its factorization.

18421380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3573 (or 3568 counting only the distinct ones).

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

The square root of 18421380 is about 4292.0135134922. The cubic root of 18421380 is about 264.1034374285.

The spelling of 18421380 in words is "eighteen million, four hundred twenty-one thousand, three hundred eighty".