20117720 has 32 divisors (see below), whose sum is σ = 51732000. Its totient is φ = 6897408.

The previous prime is 20117719. The next prime is 20117723. The reversal of 20117720 is 2771102.

It is a super-3 number, since 3×20117720³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 20117692 and 20117701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20117723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35645 + ... + 36204.

It is an arithmetic number, because the mean of its divisors is an integer number (1616625).

Almost surely, 2^20117720 is an apocalyptic number.

20117720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20117720 is an abundant number, since it is smaller than the sum of its proper divisors (31614280).

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

20117720 is a wasteful number, since it uses less digits than its factorization.

20117720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71867 (or 71863 counting only the distinct ones).

The product of its (nonzero) digits is 196, while the sum is 20.

The square root of 20117720 is about 4485.2781407623. The cubic root of 20117720 is about 271.9732888995.

Adding to 20117720 its reverse (2771102), we get a palindrome (22888822).

The spelling of 20117720 in words is "twenty million, one hundred seventeen thousand, seven hundred twenty".