18121424 has 30 divisors (see below), whose sum is σ = 36720306. Its totient is φ = 8662720.

The previous prime is 18121417. The next prime is 18121429. The reversal of 18121424 is 42412181.

It can be written as a sum of positive squares in only one way, i.e., 17909824 + 211600 = 4232^2 + 460^2 .

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 18121424.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18121429) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7394 + ... + 9534.

Almost surely, 2^18121424 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18121424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18360153).

18121424 is an abundant number, since it is smaller than the sum of its proper divisors (18598882).

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

18121424 is a wasteful number, since it uses less digits than its factorization.

18121424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2195 (or 2166 counting only the distinct ones).

The product of its digits is 512, while the sum is 23.

The square root of 18121424 is about 4256.9265908634. The cubic root of 18121424 is about 262.6621172422.

The spelling of 18121424 in words is "eighteen million, one hundred twenty-one thousand, four hundred twenty-four".