20807191 has 2 divisors, whose sum is σ = 20807192. Its totient is φ = 20807190.

The previous prime is 20807183. The next prime is 20807219. The reversal of 20807191 is 19170802.

It is an a-pointer prime, because the next prime (20807219) can be obtained adding 20807191 to its sum of digits (28).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20807191 - 2³ = 20807183 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20807291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10403595 + 10403596.

It is an arithmetic number, because the mean of its divisors is an integer number (10403596).

Almost surely, 2^20807191 is an apocalyptic number.

20807191 is a deficient number, since it is larger than the sum of its proper divisors (1).

20807191 is an equidigital number, since it uses as much as digits as its factorization.

20807191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 20807191 is about 4561.4899977968. The cubic root of 20807191 is about 275.0454624563.

Adding to 20807191 its reverse (19170802), we get a palindrome (39977993).

The spelling of 20807191 in words is "twenty million, eight hundred seven thousand, one hundred ninety-one".