20007720 has 96 divisors (see below), whose sum is σ = 65637000. Its totient is φ = 5285376.

The previous prime is 20007719. The next prime is 20007721. The reversal of 20007720 is 2770002.

It is an interprime number because it is at equal distance from previous prime (20007719) and next prime (20007721).

It can be written as a sum of positive squares in 4 ways, for example, as 12489156 + 7518564 = 3534^2 + 2742^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 20007693 and 20007702.

It is not an unprimeable number, because it can be changed into a prime (20007721) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 53454 + ... + 53826.

Almost surely, 2^20007720 is an apocalyptic number.

20007720 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 20007720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32818500).

20007720 is an abundant number, since it is smaller than the sum of its proper divisors (45629280).

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

20007720 is a wasteful number, since it uses less digits than its factorization.

20007720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 539 (or 532 counting only the distinct ones).

The product of its (nonzero) digits is 196, while the sum is 18.

The square root of 20007720 is about 4472.9989939637. The cubic root of 20007720 is about 271.4766826734.

Adding to 20007720 its reverse (2770002), we get a palindrome (22777722).

The spelling of 20007720 in words is "twenty million, seven thousand, seven hundred twenty".