20031138 has 40 divisors (see below), whose sum is σ = 45751068. Its totient is φ = 6548256.

The previous prime is 20031103. The next prime is 20031139. The reversal of 20031138 is 83113002.

It can be written as a sum of positive squares in 2 ways, for example, as 20007729 + 23409 = 4473^2 + 153^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 20031138.

It is not an unprimeable number, because it can be changed into a prime (20031139) 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, 7420 + ... + 9752.

Almost surely, 2^20031138 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20031138, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22875534).

20031138 is an abundant number, since it is smaller than the sum of its proper divisors (25719930).

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

20031138 is a wasteful number, since it uses less digits than its factorization.

20031138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2400 (or 2391 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 20031138 is about 4475.6159352652. The cubic root of 20031138 is about 271.5825578425.

The spelling of 20031138 in words is "twenty million, thirty-one thousand, one hundred thirty-eight".