20806091 has 2 divisors, whose sum is σ = 20806092. Its totient is φ = 20806090.

The previous prime is 20806081. The next prime is 20806117. The reversal of 20806091 is 19060802.

It is an a-pointer prime, because the next prime (20806117) can be obtained adding 20806091 to its sum of digits (26).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20806091 - 2¹⁸ = 20543947 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20806091.

It is not a weakly prime, because it can be changed into another prime (20806001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10403045 + 10403046.

It is an arithmetic number, because the mean of its divisors is an integer number (10403046).

Almost surely, 2^20806091 is an apocalyptic number.

20806091 is a deficient number, since it is larger than the sum of its proper divisors (1).

20806091 is an equidigital number, since it uses as much as digits as its factorization.

20806091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 20806091 is about 4561.3694215663. The cubic root of 20806091 is about 275.0406154887.

Adding to 20806091 its reverse (19060802), we get a palindrome (39866893).

The spelling of 20806091 in words is "twenty million, eight hundred six thousand, ninety-one".