21002121200 has 120 divisors (see below), whose sum is σ = 53315895600. Its totient is φ = 7928340480.

The previous prime is 21002121193. The next prime is 21002121223. The reversal of 21002121200 is 212120012.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2039264 + ... + 2049536.

It is an arithmetic number, because the mean of its divisors is an integer number (444299130).

Almost surely, 2^21002121200 is an apocalyptic number.

21002121200 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 21002121200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26657947800).

21002121200 is an abundant number, since it is smaller than the sum of its proper divisors (32313774400).

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

21002121200 is a wasteful number, since it uses less digits than its factorization.

21002121200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10579 (or 10568 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21002121200 its reverse (212120012), we get a palindrome (21214241212).

The spelling of 21002121200 in words is "twenty-one billion, two million, one hundred twenty-one thousand, two hundred".