20021002009 has 8 divisors (see below), whose sum is σ = 20159022600. Its totient is φ = 19883030400.

The previous prime is 20021001997. The next prime is 20021002019. The reversal of 20021002009 is 90020012002.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6848390025 + 13172611984 = 82755^2 + 114772^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20021002009 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20021001983 and 20021002001.

It is not an unprimeable number, because it can be changed into a prime (20021002019) 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 7 ways as a sum of consecutive naturals, for example, 1252749 + ... + 1268629.

It is an arithmetic number, because the mean of its divisors is an integer number (2519877825).

Almost surely, 2^20021002009 is an apocalyptic number.

It is an amenable number.

20021002009 is a deficient number, since it is larger than the sum of its proper divisors (138020591).

20021002009 is a wasteful number, since it uses less digits than its factorization.

20021002009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24491.

The product of its (nonzero) digits is 72, while the sum is 16.

The spelling of 20021002009 in words is "twenty billion, twenty-one million, two thousand, nine".