21221311200 has 72 divisors (see below), whose sum is σ = 69075375768. Its totient is φ = 5659015680.

The previous prime is 21221311171. The next prime is 21221311201. The reversal of 21221311200 is 211312212.

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 21221311200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221311201) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4418707 + ... + 4423506.

It is an arithmetic number, because the mean of its divisors is an integer number (959380219).

Almost surely, 2^21221311200 is an apocalyptic number.

21221311200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21221311200 is an abundant number, since it is smaller than the sum of its proper divisors (47854064568).

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

21221311200 is a wasteful number, since it uses less digits than its factorization.

21221311200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8842236 (or 8842223 counting only the distinct ones).

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

Adding to 21221311200 its reverse (211312212), we get a palindrome (21432623412).

The spelling of 21221311200 in words is "twenty-one billion, two hundred twenty-one million, three hundred eleven thousand, two hundred".