20718240 has 96 divisors (see below), whose sum is σ = 69128640. Its totient is φ = 5197824.

The previous prime is 20718233. The next prime is 20718241. The reversal of 20718240 is 4281702.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20718240.

It is not an unprimeable number, because it can be changed into a prime (20718241) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6891 + ... + 9429.

It is an arithmetic number, because the mean of its divisors is an integer number (720090).

Almost surely, 2^20718240 is an apocalyptic number.

20718240 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 20718240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34564320).

20718240 is an abundant number, since it is smaller than the sum of its proper divisors (48410400).

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

20718240 is a wasteful number, since it uses less digits than its factorization.

20718240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2574 (or 2566 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 20718240 is about 4551.7293416898. The cubic root of 20718240 is about 274.6529616857.

Adding to 20718240 its reverse (4281702), we get a palindrome (24999942).

The spelling of 20718240 in words is "twenty million, seven hundred eighteen thousand, two hundred forty".