12991897 has 4 divisors (see below), whose sum is σ = 13008996. Its totient is φ = 12974800.

The previous prime is 12991879. The next prime is 12991931. The reversal of 12991897 is 79819921.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8785296 + 4206601 = 2964^2 + 2051^2 .

It is a cyclic number.

It is not a de Polignac number, because 12991897 - 2¹⁵ = 12959129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12991807) 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 in 3 ways as a sum of consecutive naturals, for example, 7354 + ... + 8947.

It is an arithmetic number, because the mean of its divisors is an integer number (3252249).

Almost surely, 2^12991897 is an apocalyptic number.

It is an amenable number.

12991897 is a deficient number, since it is larger than the sum of its proper divisors (17099).

12991897 is an equidigital number, since it uses as much as digits as its factorization.

12991897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17098.

The product of its digits is 81648, while the sum is 46.

The square root of 12991897 is about 3604.4274163867. The cubic root of 12991897 is about 235.0846051184.

The spelling of 12991897 in words is "twelve million, nine hundred ninety-one thousand, eight hundred ninety-seven".