21311212200 has 96 divisors (see below), whose sum is σ = 66181924800. Its totient is φ = 5672911360.

The previous prime is 21311212199. The next prime is 21311212207. The reversal of 21311212200 is 221211312.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21311212200.

It is not an unprimeable number, because it can be changed into a prime (21311212207) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 310189 + ... + 372611.

It is an arithmetic number, because the mean of its divisors is an integer number (689395050).

Almost surely, 2^21311212200 is an apocalyptic number.

21311212200 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 21311212200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33090962400).

21311212200 is an abundant number, since it is smaller than the sum of its proper divisors (44870712600).

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

21311212200 is a wasteful number, since it uses less digits than its factorization.

21311212200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63011 (or 63002 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

Adding to 21311212200 its reverse (221211312), we get a palindrome (21532423512).

The spelling of 21311212200 in words is "twenty-one billion, three hundred eleven million, two hundred twelve thousand, two hundred".