20709191 has 4 divisors (see below), whose sum is σ = 20718432. Its totient is φ = 20699952.

The previous prime is 20709133. The next prime is 20709203. The reversal of 20709191 is 19190702.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20709191 - 2⁶ = 20709127 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 (20709121) 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, 1115 + ... + 6531.

It is an arithmetic number, because the mean of its divisors is an integer number (5179608).

Almost surely, 2^20709191 is an apocalyptic number.

20709191 is a deficient number, since it is larger than the sum of its proper divisors (9241).

20709191 is an equidigital number, since it uses as much as digits as its factorization.

20709191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9240.

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

The square root of 20709191 is about 4550.7352153251. The cubic root of 20709191 is about 274.6129696050.

Adding to 20709191 its reverse (19190702), we get a palindrome (39899893).

The spelling of 20709191 in words is "twenty million, seven hundred nine thousand, one hundred ninety-one".