2001121220 has 96 divisors (see below), whose sum is σ = 5008711680. Its totient is φ = 657054720.

The previous prime is 2001121217. The next prime is 2001121223. The reversal of 2001121220 is 221211002.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (2001121217) and next prime (2001121223).

It is a super-2 number, since 2×2001121220² = 8008972274268576800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (2001121223) 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, 513680 + ... + 517560.

It is an arithmetic number, because the mean of its divisors is an integer number (52174080).

Almost surely, 2^2001121220 is an apocalyptic number.

2001121220 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 2001121220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2504355840).

2001121220 is an abundant number, since it is smaller than the sum of its proper divisors (3007590460).

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

2001121220 is a wasteful number, since it uses less digits than its factorization.

2001121220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4053 (or 4051 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 2001121220 is about 44733.8934142782. The cubic root of 2001121220 is about 1260.1564473582.

Adding to 2001121220 its reverse (221211002), we get a palindrome (2222332222).

The spelling of 2001121220 in words is "two billion, one million, one hundred twenty-one thousand, two hundred twenty".