21111001200 has 360 divisors, whose sum is σ = 79675556688. Its totient is φ = 5154693120.

The previous prime is 21111001193. The next prime is 21111001243. The reversal of 21111001200 is 210011112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (360).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2259739 + ... + 2269061.

Almost surely, 2^21111001200 is an apocalyptic number.

21111001200 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 21111001200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39837778344).

21111001200 is an abundant number, since it is smaller than the sum of its proper divisors (58564555488).

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

21111001200 is a wasteful number, since it uses less digits than its factorization.

21111001200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9401 (or 9387 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21111001200 its reverse (210011112), we get a palindrome (21321012312).

The spelling of 21111001200 in words is "twenty-one billion, one hundred eleven million, one thousand, two hundred".