201221921 has 2 divisors, whose sum is σ = 201221922. Its totient is φ = 201221920.

The previous prime is 201221893. The next prime is 201221929. The reversal of 201221921 is 129122102.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 100721296 + 100500625 = 10036^2 + 10025^2 .

It is a cyclic number.

It is not a de Polignac number, because 201221921 - 2⁶ = 201221857 is a prime.

It is a super-2 number, since 2×201221921² = 80980522981860482, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 201221893 and 201221902.

It is not a weakly prime, because it can be changed into another prime (201221929) 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 as a sum of consecutive naturals, namely, 100610960 + 100610961.

It is an arithmetic number, because the mean of its divisors is an integer number (100610961).

Almost surely, 2^201221921 is an apocalyptic number.

It is an amenable number.

201221921 is a deficient number, since it is larger than the sum of its proper divisors (1).

201221921 is an equidigital number, since it uses as much as digits as its factorization.

201221921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 201221921 is about 14185.2712698771. The cubic root of 201221921 is about 585.9921032767.

The spelling of 201221921 in words is "two hundred one million, two hundred twenty-one thousand, nine hundred twenty-one".