1021021009 has 4 divisors (see below), whose sum is σ = 1056228660. Its totient is φ = 985813360.

The previous prime is 1021021007. The next prime is 1021021013. The reversal of 1021021009 is 9001201201.

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 641862225 + 379158784 = 25335^2 + 19472^2 .

It is a cyclic number.

It is not a de Polignac number, because 1021021009 - 2¹ = 1021021007 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1021020983 and 1021021001.

It is not an unprimeable number, because it can be changed into a prime (1021021007) 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 3 ways as a sum of consecutive naturals, for example, 17603782 + ... + 17603839.

It is an arithmetic number, because the mean of its divisors is an integer number (264057165).

Almost surely, 2^1021021009 is an apocalyptic number.

It is an amenable number.

1021021009 is a deficient number, since it is larger than the sum of its proper divisors (35207651).

1021021009 is an equidigital number, since it uses as much as digits as its factorization.

1021021009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35207650.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 1021021009 is about 31953.4193631918. The cubic root of 1021021009 is about 1006.9584703795.

The spelling of 1021021009 in words is "one billion, twenty-one million, twenty-one thousand, nine".