21131221200 has 120 divisors (see below), whose sum is σ = 70024610400. Its totient is φ = 5440673280.

The previous prime is 21131221193. The next prime is 21131221201. The reversal of 21131221200 is 212213112.

It is a tau number, because it is divible by the number of its divisors (120).

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 21131221200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131221201) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 268810 + ... + 338409.

It is an arithmetic number, because the mean of its divisors is an integer number (583538420).

Almost surely, 2^21131221200 is an apocalyptic number.

21131221200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21131221200 is an abundant number, since it is smaller than the sum of its proper divisors (48893389200).

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

21131221200 is a wasteful number, since it uses less digits than its factorization.

21131221200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 607269 (or 607258 counting only the distinct ones).

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

Adding to 21131221200 its reverse (212213112), we get a palindrome (21343434312).

The spelling of 21131221200 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty-one thousand, two hundred".