211221220 has 24 divisors (see below), whose sum is σ = 506931264. Its totient is φ = 72418656.

The previous prime is 211221169. The next prime is 211221229. The reversal of 211221220 is 22122112.

It is a happy number.

It is a super-2 number, since 2×211221220² = 89228807556576800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 211221220.

It is not an unprimeable number, because it can be changed into a prime (211221229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 754222 + ... + 754501.

It is an arithmetic number, because the mean of its divisors is an integer number (21122136).

Almost surely, 2^211221220 is an apocalyptic number.

211221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

211221220 is an abundant number, since it is smaller than the sum of its proper divisors (295710044).

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

211221220 is a wasteful number, since it uses less digits than its factorization.

211221220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1508739 (or 1508737 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 211221220 is about 14533.4517579273. The cubic root of 211221220 is about 595.5421652446.

Adding to 211221220 its reverse (22122112), we get a palindrome (233343332).

It can be divided in two parts, 2112 and 21220, that added together give a palindrome (23332).

The spelling of 211221220 in words is "two hundred eleven million, two hundred twenty-one thousand, two hundred twenty".