12991871 has 2 divisors, whose sum is σ = 12991872. Its totient is φ = 12991870.

The previous prime is 12991813. The next prime is 12991879. The reversal of 12991871 is 17819921.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 12991871 - 2⁶ = 12991807 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 (12991879) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6495935 + 6495936.

It is an arithmetic number, because the mean of its divisors is an integer number (6495936).

Almost surely, 2^12991871 is an apocalyptic number.

12991871 is a deficient number, since it is larger than the sum of its proper divisors (1).

12991871 is an equidigital number, since it uses as much as digits as its factorization.

12991871 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 38.

The square root of 12991871 is about 3604.4238097094. The cubic root of 12991871 is about 235.0844482974.

The spelling of 12991871 in words is "twelve million, nine hundred ninety-one thousand, eight hundred seventy-one".