211221211220 has 24 divisors (see below), whose sum is σ = 448137378024. Its totient is φ = 83617468416.

The previous prime is 211221211217. The next prime is 211221211231. The reversal of 211221211220 is 22112122112.

It can be written as a sum of positive squares in 4 ways, for example, as 13548494404 + 197672716816 = 116398^2 + 444604^2 .

It is a super-2 number, since 2×211221211220² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54436517 + ... + 54440396.

It is an arithmetic number, because the mean of its divisors is an integer number (18672390751).

Almost surely, 2^211221211220 is an apocalyptic number.

211221211220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

211221211220 is an abundant number, since it is smaller than the sum of its proper divisors (236916166804).

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

211221211220 is a wasteful number, since it uses less digits than its factorization.

211221211220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108877019 (or 108877017 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 211221211220 its reverse (22112122112), we get a palindrome (233333333332).

The spelling of 211221211220 in words is "two hundred eleven billion, two hundred twenty-one million, two hundred eleven thousand, two hundred twenty".