2121221220 has 48 divisors (see below), whose sum is σ = 6000667008. Its totient is φ = 559825920.

The previous prime is 2121221209. The next prime is 2121221227. The reversal of 2121221220 is 221221212.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 2121221220.

It is not an unprimeable number, because it can be changed into a prime (2121221227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 176416 + ... + 188055.

It is an arithmetic number, because the mean of its divisors is an integer number (125013896).

Almost surely, 2^2121221220 is an apocalyptic number.

2121221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2121221220 is an abundant number, since it is smaller than the sum of its proper divisors (3879445788).

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

2121221220 is a wasteful number, since it uses less digits than its factorization.

2121221220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364580 (or 364578 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 2121221220 is about 46056.7174253659. The cubic root of 2121221220 is about 1284.8782798401.

Adding to 2121221220 its reverse (221221212), we get a palindrome (2342442432).

The spelling of 2121221220 in words is "two billion, one hundred twenty-one million, two hundred twenty-one thousand, two hundred twenty".