20181312 has 140 divisors (see below), whose sum is σ = 63619380. Its totient is φ = 6303744.

The previous prime is 20181311. The next prime is 20181313. The reversal of 20181312 is 21318102.

It is an interprime number because it is at equal distance from previous prime (20181311) and next prime (20181313).

It can be written as a sum of positive squares in 2 ways, for example, as 17438976 + 2742336 = 4176^2 + 1656^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20181311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 88014 + ... + 88242.

Almost surely, 2^20181312 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 20181312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31809690).

20181312 is an abundant number, since it is smaller than the sum of its proper divisors (43438068).

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

20181312 is a wasteful number, since it uses less digits than its factorization.

20181312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270 (or 251 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 20181312 is about 4492.3615170643. The cubic root of 20181312 is about 272.2595561612.

Adding to 20181312 its reverse (21318102), we get a palindrome (41499414).

The spelling of 20181312 in words is "twenty million, one hundred eighty-one thousand, three hundred twelve".