21011222221200 has 150 divisors (see below), whose sum is σ = 75407590582434. Its totient is φ = 5602992583680.

The previous prime is 21011222221189. The next prime is 21011222221207. The reversal of 21011222221200 is 212222211012.

It is a happy number.

21011222221200 is a `hidden beast` number, since 2 + 10 + 11 + 222 + 221 + 200 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 38522697984 + 20972699523216 = 196272^2 + 4579596^2 .

It is a tau number, because it is divible by the number of its divisors (150).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21011222221207) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 324214857 + ... + 324279656.

Almost surely, 2^{21011222221200} is an apocalyptic number.

21011222221200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21011222221200 is an abundant number, since it is smaller than the sum of its proper divisors (54396368361234).

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

21011222221200 is a wasteful number, since it uses less digits than its factorization.

21011222221200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 648494543 (or 648494523 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21011222221200 its reverse (212222211012), we get a palindrome (21223444432212).

The spelling of 21011222221200 in words is "twenty-one trillion, eleven billion, two hundred twenty-two million, two hundred twenty-one thousand, two hundred".