20115540 has 72 divisors (see below), whose sum is σ = 63292320. Its totient is φ = 5362848.

The previous prime is 20115527. The next prime is 20115553. The reversal of 20115540 is 4551102.

It is an interprime number because it is at equal distance from previous prime (20115527) and next prime (20115553).

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

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 2791 + ... + 6929.

It is an arithmetic number, because the mean of its divisors is an integer number (879060).

Almost surely, 2^20115540 is an apocalyptic number.

20115540 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 20115540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31646160).

20115540 is an abundant number, since it is smaller than the sum of its proper divisors (43176780).

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

20115540 is a wasteful number, since it uses less digits than its factorization.

20115540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4163 (or 4149 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 20115540 is about 4485.0351169194. The cubic root of 20115540 is about 271.9634646718.

Adding to 20115540 its reverse (4551102), we get a palindrome (24666642).

The spelling of 20115540 in words is "twenty million, one hundred fifteen thousand, five hundred forty".