211221100 has 54 divisors (see below), whose sum is σ = 483825804. Its totient is φ = 80028000.

The previous prime is 211221091. The next prime is 211221169. The reversal of 211221100 is 1122112.

It is a super-3 number, since 3×211221100³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 33175 + ... + 39025.

Almost surely, 2^211221100 is an apocalyptic number.

211221100 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 211221100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (241912902).

211221100 is an abundant number, since it is smaller than the sum of its proper divisors (272604704).

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

211221100 is a wasteful number, since it uses less digits than its factorization.

211221100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5903 (or 5877 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 211221100 is about 14533.4476295200. The cubic root of 211221100 is about 595.5420524638.

Adding to 211221100 its reverse (1122112), we get a palindrome (212343212).

It can be divided in two parts, 21122 and 1100, that added together give a palindrome (22222).

The spelling of 211221100 in words is "two hundred eleven million, two hundred twenty-one thousand, one hundred".