31818816 has 84 divisors (see below), whose sum is σ = 93730572. Its totient is φ = 10312704.

The previous prime is 31818811. The next prime is 31818823. The reversal of 31818816 is 61881813.

It can be written as a sum of positive squares in 2 ways, for example, as 28132416 + 3686400 = 5304^2 + 1920^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

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

It is not an unprimeable number, because it can be changed into a prime (31818811) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20566 + ... + 22058.

Almost surely, 2^31818816 is an apocalyptic number.

31818816 is a gapful number since it is divisible by the number (36) 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 31818816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46865286).

31818816 is an abundant number, since it is smaller than the sum of its proper divisors (61911756).

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

31818816 is a wasteful number, since it uses less digits than its factorization.

31818816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1548 (or 1535 counting only the distinct ones).

The product of its digits is 9216, while the sum is 36.

The square root of 31818816 is about 5640.8169621075. The cubic root of 31818816 is about 316.8798849661.

Subtracting from 31818816 its product of digits (9216), we obtain a square (31809600 = 5640²).

The spelling of 31818816 in words is "thirty-one million, eight hundred eighteen thousand, eight hundred sixteen".