8021720520 has 512 divisors, whose sum is σ = 30656102400. Its totient is φ = 1848268800.

The previous prime is 8021720513. The next prime is 8021720569. The reversal of 8021720520 is 250271208.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 20944249 + ... + 20944631.

It is an arithmetic number, because the mean of its divisors is an integer number (59875200).

Almost surely, 2^8021720520 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 8021720520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15328051200).

8021720520 is an abundant number, since it is smaller than the sum of its proper divisors (22634381880).

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

8021720520 is a wasteful number, since it uses less digits than its factorization.

8021720520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 498 (or 488 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 8021720520 is about 89564.0581930051. The cubic root of 8021720520 is about 2001.8084076713.

Adding to 8021720520 its reverse (250271208), we get a palindrome (8271991728).

The spelling of 8021720520 in words is "eight billion, twenty-one million, seven hundred twenty thousand, five hundred twenty".