20615191 has 2 divisors, whose sum is σ = 20615192. Its totient is φ = 20615190.

The previous prime is 20615173. The next prime is 20615207. The reversal of 20615191 is 19151602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20615191 - 2²¹ = 18518039 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20615591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10307595 + 10307596.

It is an arithmetic number, because the mean of its divisors is an integer number (10307596).

Almost surely, 2^20615191 is an apocalyptic number.

20615191 is a deficient number, since it is larger than the sum of its proper divisors (1).

20615191 is an equidigital number, since it uses as much as digits as its factorization.

20615191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 540, while the sum is 25.

The square root of 20615191 is about 4540.3954673574. The cubic root of 20615191 is about 274.1968456025.

Adding to 20615191 its reverse (19151602), we get a palindrome (39766793).

The spelling of 20615191 in words is "twenty million, six hundred fifteen thousand, one hundred ninety-one".