21111211212120 has 128 divisors (see below), whose sum is σ = 70377305241600. Its totient is φ = 5629128227712.

The previous prime is 21111211212071. The next prime is 21111211212139. The reversal of 21111211212120 is 2121211211112.

It is a happy number.

21111211212120 is a `hidden beast` number, since 211 + 1 + 121 + 1 + 212 + 120 = 666.

21111211212120 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

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

It is a junction number, because it is equal to n+sod(n) for n = 21111211212093 and 21111211212102.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10669369 + ... + 12492311.

It is an arithmetic number, because the mean of its divisors is an integer number (549822697200).

Almost surely, 2^{21111211212120} is an apocalyptic number.

21111211212120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21111211212120 is an abundant number, since it is smaller than the sum of its proper divisors (49266094029480).

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

21111211212120 is a wasteful number, since it uses less digits than its factorization.

21111211212120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1833686 (or 1833676 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 18.

Adding to 21111211212120 its reverse (2121211211112), we get a palindrome (23232422423232).

The spelling of 21111211212120 in words is "twenty-one trillion, one hundred eleven billion, two hundred eleven million, two hundred twelve thousand, one hundred twenty".