201221021 has 4 divisors (see below), whose sum is σ = 203001852. Its totient is φ = 199440192.

The previous prime is 201221017. The next prime is 201221099. The reversal of 201221021 is 120122102.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12460900 + 188760121 = 3530^2 + 13739^2 .

It is a cyclic number.

It is not a de Polignac number, because 201221021 - 2² = 201221017 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 201220993 and 201221011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (201221011) 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 3 ways as a sum of consecutive naturals, for example, 890246 + ... + 890471.

It is an arithmetic number, because the mean of its divisors is an integer number (50750463).

Almost surely, 2^201221021 is an apocalyptic number.

It is an amenable number.

201221021 is a deficient number, since it is larger than the sum of its proper divisors (1780831).

201221021 is a wasteful number, since it uses less digits than its factorization.

201221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1780830.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 201221021 is about 14185.2395467965. The cubic root of 201221021 is about 585.9912296249.

Adding to 201221021 its reverse (120122102), we get a palindrome (321343123).

The spelling of 201221021 in words is "two hundred one million, two hundred twenty-one thousand, twenty-one".