21021121221220 has 24 divisors (see below), whose sum is σ = 44144840457144. Its totient is φ = 8408355937536.

The previous prime is 21021121221209. The next prime is 21021121221277. The reversal of 21021121221220 is 2212212112012.

It can be written as a sum of positive squares in 4 ways, for example, as 520438159396 + 20500683061824 = 721414^2 + 4527768^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3907107 + ... + 7570186.

It is an arithmetic number, because the mean of its divisors is an integer number (1839368352381).

Almost surely, 2^{21021121221220} is an apocalyptic number.

21021121221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021121221220 is an abundant number, since it is smaller than the sum of its proper divisors (23123719235924).

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

21021121221220 is a wasteful number, since it uses less digits than its factorization.

21021121221220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11568879 (or 11568877 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21021121221220 its reverse (2212212112012), we get a palindrome (23233333333232).

The spelling of 21021121221220 in words is "twenty-one trillion, twenty-one billion, one hundred twenty-one million, two hundred twenty-one thousand, two hundred twenty".