20191709 has 2 divisors, whose sum is σ = 20191710. Its totient is φ = 20191708.

The previous prime is 20191693. The next prime is 20191729. The reversal of 20191709 is 90719102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11323225 + 8868484 = 3365^2 + 2978^2 .

It is a cyclic number.

It is not a de Polignac number, because 20191709 - 2⁴ = 20191693 is a prime.

It is a super-2 number, since 2×20191709² = 815410224681362, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20191729) 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 as a sum of consecutive naturals, namely, 10095854 + 10095855.

It is an arithmetic number, because the mean of its divisors is an integer number (10095855).

Almost surely, 2^20191709 is an apocalyptic number.

It is an amenable number.

20191709 is a deficient number, since it is larger than the sum of its proper divisors (1).

20191709 is an equidigital number, since it uses as much as digits as its factorization.

20191709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1134, while the sum is 29.

The square root of 20191709 is about 4493.5185545405. The cubic root of 20191709 is about 272.3063023232.

The spelling of 20191709 in words is "twenty million, one hundred ninety-one thousand, seven hundred nine".