201221100 has 216 divisors, whose sum is σ = 662957568. Its totient is φ = 51004800.

The previous prime is 201221099. The next prime is 201221101. The reversal of 201221100 is 1122102.

It is an interprime number because it is at equal distance from previous prime (201221099) and next prime (201221101).

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

It is not an unprimeable number, because it can be changed into a prime (201221101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2834065 + ... + 2834135.

It is an arithmetic number, because the mean of its divisors is an integer number (3069248).

Almost surely, 2^201221100 is an apocalyptic number.

201221100 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 201221100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (331478784).

201221100 is an abundant number, since it is smaller than the sum of its proper divisors (461736468).

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

201221100 is a wasteful number, since it uses less digits than its factorization.

201221100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205 (or 195 counting only the distinct ones).

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

The square root of 201221100 is about 14185.2423313809. The cubic root of 201221100 is about 585.9913063122.

Adding to 201221100 its reverse (1122102), we get a palindrome (202343202).

The spelling of 201221100 in words is "two hundred one million, two hundred twenty-one thousand, one hundred".