20121221208 has 128 divisors (see below), whose sum is σ = 55363875840. Its totient is φ = 6043392000.

The previous prime is 20121221161. The next prime is 20121221249. The reversal of 20121221208 is 80212212102.

It is a congruent number.

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, 20594416 + ... + 20595392.

It is an arithmetic number, because the mean of its divisors is an integer number (432530280).

Almost surely, 2^20121221208 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20121221208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27681937920).

20121221208 is an abundant number, since it is smaller than the sum of its proper divisors (35242654632).

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

20121221208 is a wasteful number, since it uses less digits than its factorization.

20121221208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1609 (or 1605 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The spelling of 20121221208 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-one thousand, two hundred eight".