20021001220 has 144 divisors (see below), whose sum is σ = 47466699840. Its totient is φ = 7085295360.

The previous prime is 20021001193. The next prime is 20021001229. The reversal of 20021001220 is 2210012002.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 20021001197 and 20021001206.

It is not an unprimeable number, because it can be changed into a prime (20021001229) 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 47 ways as a sum of consecutive naturals, for example, 17827579 + ... + 17828701.

It is an arithmetic number, because the mean of its divisors is an integer number (329629860).

Almost surely, 2^20021001220 is an apocalyptic number.

20021001220 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 20021001220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23733349920).

20021001220 is an abundant number, since it is smaller than the sum of its proper divisors (27445698620).

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

20021001220 is a wasteful number, since it uses less digits than its factorization.

20021001220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1346 (or 1333 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 20021001220 its reverse (2210012002), we get a palindrome (22231013222).

The spelling of 20021001220 in words is "twenty billion, twenty-one million, one thousand, two hundred twenty".