201021009 has 16 divisors (see below), whose sum is σ = 307662720. Its totient is φ = 114364800.

The previous prime is 201020987. The next prime is 201021043. The reversal of 201021009 is 900120102.

It is a happy number.

It is not a de Polignac number, because 201021009 - 2⁵ = 201020977 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (201021089) 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 15 ways as a sum of consecutive naturals, for example, 16092 + ... + 25709.

It is an arithmetic number, because the mean of its divisors is an integer number (19228920).

Almost surely, 2^201021009 is an apocalyptic number.

It is an amenable number.

201021009 is a deficient number, since it is larger than the sum of its proper divisors (106641711).

201021009 is a wasteful number, since it uses less digits than its factorization.

201021009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42040.

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 201021009 is about 14178.1877897001. The cubic root of 201021009 is about 585.7970084771.

The spelling of 201021009 in words is "two hundred one million, twenty-one thousand, nine".