18431216 has 30 divisors (see below), whose sum is σ = 37700712. Its totient is φ = 8727840.

The previous prime is 18431207. The next prime is 18431233. The reversal of 18431216 is 61213481.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4181 + ... + 7371.

Almost surely, 2^18431216 is an apocalyptic number.

18431216 is a gapful number since it is divisible by the number (16) 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 18431216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18850356).

18431216 is an abundant number, since it is smaller than the sum of its proper divisors (19269496).

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

18431216 is a wasteful number, since it uses less digits than its factorization.

18431216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3237 (or 3212 counting only the distinct ones).

The product of its digits is 1152, while the sum is 26.

The square root of 18431216 is about 4293.1592097196. The cubic root of 18431216 is about 264.1504346169.

Adding to 18431216 its reverse (61213481), we get a palindrome (79644697).

The spelling of 18431216 in words is "eighteen million, four hundred thirty-one thousand, two hundred sixteen".