20615591 has 2 divisors, whose sum is σ = 20615592. Its totient is φ = 20615590.

The previous prime is 20615537. The next prime is 20615597. The reversal of 20615591 is 19551602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20615591 - 2¹⁰ = 20614567 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20615597) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10307795 + 10307796.

It is an arithmetic number, because the mean of its divisors is an integer number (10307796).

Almost surely, 2^20615591 is an apocalyptic number.

20615591 is a deficient number, since it is larger than the sum of its proper divisors (1).

20615591 is an equidigital number, since it uses as much as digits as its factorization.

20615591 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2700, while the sum is 29.

The square root of 20615591 is about 4540.4395161702. The cubic root of 20615591 is about 274.1986190201.

The spelling of 20615591 in words is "twenty million, six hundred fifteen thousand, five hundred ninety-one".