12865991 has 6 divisors (see below), whose sum is σ = 13667640. Its totient is φ = 12108896.

The previous prime is 12865969. The next prime is 12865997. The reversal of 12865991 is 19956821.

It is a happy number.

It is not a de Polignac number, because 12865991 - 2⁶ = 12865927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12865997) 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 in 5 ways as a sum of consecutive naturals, for example, 21971 + ... + 22548.

It is an arithmetic number, because the mean of its divisors is an integer number (2277940).

Almost surely, 2^12865991 is an apocalyptic number.

12865991 is a deficient number, since it is larger than the sum of its proper divisors (801649).

12865991 is an equidigital number, since it uses as much as digits as its factorization.

12865991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44553 (or 44536 counting only the distinct ones).

The product of its digits is 38880, while the sum is 41.

The square root of 12865991 is about 3586.9194303748. The cubic root of 12865991 is about 234.3227278034.

The spelling of 12865991 in words is "twelve million, eight hundred sixty-five thousand, nine hundred ninety-one".