20018440 has 64 divisors (see below), whose sum is σ = 49034160. Its totient is φ = 7311360.

The previous prime is 20018437. The next prime is 20018459. The reversal of 20018440 is 4481002.

It can be written as a sum of positive squares in 8 ways, for example, as 7387524 + 12630916 = 2718^2 + 3554^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 71100 + ... + 71380.

Almost surely, 2^20018440 is an apocalyptic number.

20018440 is a gapful number since it is divisible by the number (20) 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 20018440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24517080).

20018440 is an abundant number, since it is smaller than the sum of its proper divisors (29015720).

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

20018440 is a wasteful number, since it uses less digits than its factorization.

20018440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442 (or 438 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 19.

The square root of 20018440 is about 4474.1971346824. The cubic root of 20018440 is about 271.5251591353.

Adding to 20018440 its reverse (4481002), we get a palindrome (24499442).

The spelling of 20018440 in words is "twenty million, eighteen thousand, four hundred forty".