20717009 has 4 divisors (see below), whose sum is σ = 20751204. Its totient is φ = 20682816.

The previous prime is 20716987. The next prime is 20717023. The reversal of 20717009 is 90071702.

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 6390784 + 14326225 = 2528^2 + 3785^2 .

It is a cyclic number.

It is not a de Polignac number, because 20717009 - 2⁸ = 20716753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20717209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16172 + ... + 17405.

It is an arithmetic number, because the mean of its divisors is an integer number (5187801).

Almost surely, 2^20717009 is an apocalyptic number.

It is an amenable number.

20717009 is a deficient number, since it is larger than the sum of its proper divisors (34195).

20717009 is an equidigital number, since it uses as much as digits as its factorization.

20717009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34194.

The product of its (nonzero) digits is 882, while the sum is 26.

The square root of 20717009 is about 4551.5941163509. The cubic root of 20717009 is about 274.6475219621.

The spelling of 20717009 in words is "twenty million, seven hundred seventeen thousand, nine".