20408191 has 2 divisors, whose sum is σ = 20408192. Its totient is φ = 20408190.

The previous prime is 20408189. The next prime is 20408231. The reversal of 20408191 is 19180402.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20408191 - 2¹ = 20408189 is a prime.

Together with 20408189, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20448191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10204095 + 10204096.

It is an arithmetic number, because the mean of its divisors is an integer number (10204096).

Almost surely, 2^20408191 is an apocalyptic number.

20408191 is a deficient number, since it is larger than the sum of its proper divisors (1).

20408191 is an equidigital number, since it uses as much as digits as its factorization.

20408191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 20408191 is about 4517.5425841933. The cubic root of 20408191 is about 273.2760070471.

Adding to 20408191 its reverse (19180402), we get a palindrome (39588593).

The spelling of 20408191 in words is "twenty million, four hundred eight thousand, one hundred ninety-one".