21201021200 has 60 divisors (see below), whose sum is σ = 51046386468. Its totient is φ = 8461939200.

The previous prime is 21201021173. The next prime is 21201021211. The reversal of 21201021200 is 212010212.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 133079296 + 21067941904 = 11536^2 + 145148^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 126914 + ... + 241886.

Almost surely, 2^21201021200 is an apocalyptic number.

21201021200 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 21201021200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25523193234).

21201021200 is an abundant number, since it is smaller than the sum of its proper divisors (29845365268).

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

21201021200 is a wasteful number, since it uses less digits than its factorization.

21201021200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115452 (or 115441 counting only the distinct ones).

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

Adding to 21201021200 its reverse (212010212), we get a palindrome (21413031412).

21201021200 divided by its reverse (212010212) gives a square (100 = 10²).

The spelling of 21201021200 in words is "twenty-one billion, two hundred one million, twenty-one thousand, two hundred".