2009921021 has 2 divisors, whose sum is σ = 2009921022. Its totient is φ = 2009921020.

The previous prime is 2009920981. The next prime is 2009921027. The reversal of 2009921021 is 1201299002.

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., 1313700025 + 696220996 = 36245^2 + 26386^2 .

It is a cyclic number.

It is not a de Polignac number, because 2009921021 - 2¹⁸ = 2009658877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2009921027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1004960510 + 1004960511.

It is an arithmetic number, because the mean of its divisors is an integer number (1004960511).

Almost surely, 2^2009921021 is an apocalyptic number.

It is an amenable number.

2009921021 is a deficient number, since it is larger than the sum of its proper divisors (1).

2009921021 is an equidigital number, since it uses as much as digits as its factorization.

2009921021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 2009921021 is about 44832.1427214895. The cubic root of 2009921021 is about 1262.0008985052. Note that the first 3 decimals are identical.

The spelling of 2009921021 in words is "two billion, nine million, nine hundred twenty-one thousand, twenty-one".