21211121111220 has 72 divisors (see below), whose sum is σ = 64345101486120. Its totient is φ = 5655885707520.

The previous prime is 21211121111203. The next prime is 21211121111269. The reversal of 21211121111220 is 2211112111212.

It is a happy number.

21211121111220 is a `hidden beast` number, since 2 + 1 + 211 + 121 + 111 + 220 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 703645834896 + 20507475276324 = 838836^2 + 4528518^2 .

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 = 21211121111193 and 21211121111202.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1830271 + ... + 6765510.

It is an arithmetic number, because the mean of its divisors is an integer number (893681965085).

Almost surely, 2^{21211121111220} is an apocalyptic number.

21211121111220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21211121111220 is an abundant number, since it is smaller than the sum of its proper divisors (43133980374900).

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

21211121111220 is a wasteful number, since it uses less digits than its factorization.

21211121111220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8609505 (or 8609500 counting only the distinct ones).

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

Adding to 21211121111220 its reverse (2211112111212), we get a palindrome (23422233222432).

The spelling of 21211121111220 in words is "twenty-one trillion, two hundred eleven billion, one hundred twenty-one million, one hundred eleven thousand, two hundred twenty".