2001221001220 has 96 divisors (see below), whose sum is σ = 4840493898240. Its totient is φ = 680784030720.

The previous prime is 2001221001211. The next prime is 2001221001229. The reversal of 2001221001220 is 221001221002.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (2001221001211) and next prime (2001221001229).

It is a self number, because there is not a number n which added to its sum of digits gives 2001221001220.

It is not an unprimeable number, because it can be changed into a prime (2001221001229) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11034312 + ... + 11214208.

It is an arithmetic number, because the mean of its divisors is an integer number (50421811440).

Almost surely, 2^{2001221001220} is an apocalyptic number.

2001221001220 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 2001221001220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2420246949120).

2001221001220 is an abundant number, since it is smaller than the sum of its proper divisors (2839272897020).

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

2001221001220 is a wasteful number, since it uses less digits than its factorization.

2001221001220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180533 (or 180531 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 2001221001220 its reverse (221001221002), we get a palindrome (2222222222222).

The spelling of 2001221001220 in words is "two trillion, one billion, two hundred twenty-one million, one thousand, two hundred twenty".