20115709 has 4 divisors (see below), whose sum is σ = 21299004. Its totient is φ = 18932416.

The previous prime is 20115659. The next prime is 20115713. The reversal of 20115709 is 90751102.

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 15578809 + 4536900 = 3947^2 + 2130^2 .

It is a cyclic number.

It is not a de Polignac number, because 20115709 - 2⁹ = 20115197 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20119709) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 591622 + ... + 591655.

It is an arithmetic number, because the mean of its divisors is an integer number (5324751).

Almost surely, 2^20115709 is an apocalyptic number.

It is an amenable number.

20115709 is a deficient number, since it is larger than the sum of its proper divisors (1183295).

20115709 is a wasteful number, since it uses less digits than its factorization.

20115709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1183294.

The product of its (nonzero) digits is 630, while the sum is 25.

The square root of 20115709 is about 4485.0539573120. The cubic root of 20115709 is about 271.9642263001.

The spelling of 20115709 in words is "twenty million, one hundred fifteen thousand, seven hundred nine".