21221220202120 has 128 divisors (see below), whose sum is σ = 48129035090400. Its totient is φ = 8420986699776.

The previous prime is 21221220202109. The next prime is 21221220202157. The reversal of 21221220202120 is 2120202212212.

It can be written as a sum of positive squares in 16 ways, for example, as 13125158053956 + 8096062148164 = 3622866^2 + 2845358^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6405437584 + ... + 6405440896.

Almost surely, 2^{21221220202120} is an apocalyptic number.

21221220202120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21221220202120 is an abundant number, since it is smaller than the sum of its proper divisors (26907814888280).

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

21221220202120 is a wasteful number, since it uses less digits than its factorization.

21221220202120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5627 (or 5623 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 19.

Adding to 21221220202120 its reverse (2120202212212), we get a palindrome (23341422414332).

The spelling of 21221220202120 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty million, two hundred two thousand, one hundred twenty".