2121021009 has 12 divisors (see below), whose sum is σ = 3067283076. Its totient is φ = 1412358912.

The previous prime is 2121020989. The next prime is 2121021013. The reversal of 2121021009 is 9001201212.

It can be written as a sum of positive squares in 2 ways, for example, as 1128960000 + 992061009 = 33600^2 + 31497^2 .

It is not a de Polignac number, because 2121021009 - 2⁸ = 2121020753 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2121020982 and 2121021000.

It is not an unprimeable number, because it can be changed into a prime (2121021079) 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 11 ways as a sum of consecutive naturals, for example, 129784 + ... + 145209.

It is an arithmetic number, because the mean of its divisors is an integer number (255606923).

Almost surely, 2^2121021009 is an apocalyptic number.

It is an amenable number.

2121021009 is a deficient number, since it is larger than the sum of its proper divisors (946262067).

2121021009 is a wasteful number, since it uses less digits than its factorization.

2121021009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 275856 (or 275853 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 2121021009 is about 46054.5438474859. The cubic root of 2121021009 is about 1284.8378542499.

The spelling of 2121021009 in words is "two billion, one hundred twenty-one million, twenty-one thousand, nine".