21121212121200 has 360 divisors, whose sum is σ = 76025472280576. Its totient is φ = 5631262560000.

The previous prime is 21121212121069. The next prime is 21121212121223. The reversal of 21121212121200 is 212121212112.

21121212121200 is a `hidden beast` number, since 211 + 2 + 121 + 212 + 120 + 0 = 666.

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

It is a super-2 number, since 2×21121212121200² (a number of 27 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 609523875 + ... + 609558525.

Almost surely, 2^{21121212121200} is an apocalyptic number.

21121212121200 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 21121212121200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38012736140288).

21121212121200 is an abundant number, since it is smaller than the sum of its proper divisors (54904260159376).

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

21121212121200 is a wasteful number, since it uses less digits than its factorization.

21121212121200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40955 (or 40932 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21121212121200 its reverse (212121212112), we get a palindrome (21333333333312).

The spelling of 21121212121200 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twelve million, one hundred twenty-one thousand, two hundred".