1291608391 has 4 divisors (see below), whose sum is σ = 1359587800. Its totient is φ = 1223628984.

The previous prime is 1291608389. The next prime is 1291608421. The reversal of 1291608391 is 1938061921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1938061921 = 19 ⋅102003259.

It is a cyclic number.

It is not a de Polignac number, because 1291608391 - 2¹ = 1291608389 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 (1291608091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33989676 + ... + 33989713.

It is an arithmetic number, because the mean of its divisors is an integer number (339896950).

Almost surely, 2^1291608391 is an apocalyptic number.

1291608391 is a deficient number, since it is larger than the sum of its proper divisors (67979409).

1291608391 is an equidigital number, since it uses as much as digits as its factorization.

1291608391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67979408.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 1291608391 is about 35938.9536714691. The cubic root of 1291608391 is about 1089.0394677529.

The spelling of 1291608391 in words is "one billion, two hundred ninety-one million, six hundred eight thousand, three hundred ninety-one".