201221001 has 24 divisors (see below), whose sum is σ = 307026720. Its totient is φ = 126639936.

The previous prime is 201220991. The next prime is 201221003. The reversal of 201221001 is 100122102.

It is not a de Polignac number, because 201221001 - 2¹⁴ = 201204617 is a prime.

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 (201221003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 50581 + ... + 54413.

It is an arithmetic number, because the mean of its divisors is an integer number (12792780).

Almost surely, 2^201221001 is an apocalyptic number.

It is an amenable number.

201221001 is a deficient number, since it is larger than the sum of its proper divisors (105805719).

201221001 is a wasteful number, since it uses less digits than its factorization.

201221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4165 (or 4162 counting only the distinct ones).

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

The square root of 201221001 is about 14185.2388418384. The cubic root of 201221001 is about 585.9912102103.

Adding to 201221001 its reverse (100122102), we get a palindrome (301343103).

The spelling of 201221001 in words is "two hundred one million, two hundred twenty-one thousand, one".