21221202002120 has 128 divisors (see below), whose sum is σ = 49475605788000. Its totient is φ = 8182274580480.

The previous prime is 21221202002111. The next prime is 21221202002129. The reversal of 21221202002120 is 2120020212212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21221202002111) and next prime (21221202002129).

It can be written as a sum of positive squares in 16 ways, for example, as 10347840841636 + 10873361160484 = 3216806^2 + 3297478^2 .

It is not an unprimeable number, because it can be changed into a prime (21221202002129) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2243014190 + ... + 2243023650.

Almost surely, 2^{21221202002120} is an apocalyptic number.

21221202002120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21221202002120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24737802894000).

21221202002120 is an abundant number, since it is smaller than the sum of its proper divisors (28254403785880).

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

21221202002120 is a wasteful number, since it uses less digits than its factorization.

21221202002120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12483 (or 12479 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21221202002120 its reverse (2120020212212), we get a palindrome (23341222214332).

The spelling of 21221202002120 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred two million, two thousand, one hundred twenty".