211111211220 has 384 divisors, whose sum is σ = 767168962560. Its totient is φ = 42123110400.

The previous prime is 211111211177. The next prime is 211111211237. The reversal of 211111211220 is 22112111112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 211111211220.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 72720289 + ... + 72723191.

It is an arithmetic number, because the mean of its divisors is an integer number (1997835840).

Almost surely, 2^211111211220 is an apocalyptic number.

211111211220 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 211111211220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (383584481280).

211111211220 is an abundant number, since it is smaller than the sum of its proper divisors (556057751340).

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

211111211220 is a wasteful number, since it uses less digits than its factorization.

211111211220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3655 (or 3653 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 211111211220 its reverse (22112111112), we get a palindrome (233223322332).

The spelling of 211111211220 in words is "two hundred eleven billion, one hundred eleven million, two hundred eleven thousand, two hundred twenty".