12661591 has 2 divisors, whose sum is σ = 12661592. Its totient is φ = 12661590.

The previous prime is 12661589. The next prime is 12661613. The reversal of 12661591 is 19516621.

12661591 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is an emirp because it is prime and its reverse (19516621) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12661591 - 2¹ = 12661589 is a prime.

Together with 12661589, 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 (12661091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6330795 + 6330796.

It is an arithmetic number, because the mean of its divisors is an integer number (6330796).

Almost surely, 2^12661591 is an apocalyptic number.

12661591 is a deficient number, since it is larger than the sum of its proper divisors (1).

12661591 is an equidigital number, since it uses as much as digits as its factorization.

12661591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 31.

The square root of 12661591 is about 3558.3129429548. The cubic root of 12661591 is about 233.0752150228.

The spelling of 12661591 in words is "twelve million, six hundred sixty-one thousand, five hundred ninety-one".