21021021200 has 60 divisors (see below), whose sum is σ = 52244515140. Its totient is φ = 8118458880.

The previous prime is 21021021199. The next prime is 21021021269. The reversal of 21021021200 is 212012012.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 1260534016 + 19760487184 = 35504^2 + 140572^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 894479 + ... + 917678.

It is an arithmetic number, because the mean of its divisors is an integer number (870741919).

Almost surely, 2^21021021200 is an apocalyptic number.

21021021200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021021200 is an abundant number, since it is smaller than the sum of its proper divisors (31223493940).

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

21021021200 is a wasteful number, since it uses less digits than its factorization.

21021021200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1812204 (or 1812193 counting only the distinct ones).

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

Adding to 21021021200 its reverse (212012012), we get a palindrome (21233033212).

The spelling of 21021021200 in words is "twenty-one billion, twenty-one million, twenty-one thousand, two hundred".