211221000 has 128 divisors (see below), whose sum is σ = 732326400. Its totient is φ = 56318400.

The previous prime is 211220993. The next prime is 211221013. The reversal of 211221000 is 122112.

It is a super-2 number, since 2×211221000² = 89228621682000000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23089 + ... + 30911.

It is an arithmetic number, because the mean of its divisors is an integer number (5721300).

Almost surely, 2^211221000 is an apocalyptic number.

211221000 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 211221000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (366163200).

211221000 is an abundant number, since it is smaller than the sum of its proper divisors (521105400).

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

211221000 is a wasteful number, since it uses less digits than its factorization.

211221000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7853 (or 7833 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 211221000 is about 14533.4441891797. Note that the first 3 decimals coincide. The cubic root of 211221000 is about 595.5419584798.

Adding to 211221000 its reverse (122112), we get a palindrome (211343112).

It can be divided in two parts, 21122 and 1000, that added together give a palindrome (22122).

The spelling of 211221000 in words is "two hundred eleven million, two hundred twenty-one thousand".