20121221220 has 96 divisors (see below), whose sum is σ = 56586636288. Its totient is φ = 5342182272.

The previous prime is 20121221161. The next prime is 20121221249. The reversal of 20121221220 is 2212212102.

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 20121221220.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 22786899 + ... + 22787781.

It is an arithmetic number, because the mean of its divisors is an integer number (589444128).

Almost surely, 2^20121221220 is an apocalyptic number.

20121221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20121221220 is an abundant number, since it is smaller than the sum of its proper divisors (36465415068).

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

20121221220 is a wasteful number, since it uses less digits than its factorization.

20121221220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2129 (or 2127 counting only the distinct ones).

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

Adding to 20121221220 its reverse (2212212102), we get a palindrome (22333433322).

The spelling of 20121221220 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-one thousand, two hundred twenty".