1291731897 has 8 divisors (see below), whose sum is σ = 1746567360. Its totient is φ = 849025520.

The previous prime is 1291731877. The next prime is 1291731941. The reversal of 1291731897 is 7981371921.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1291731897 - 2⁷ = 1291731769 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1291731817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3032022 + ... + 3032447.

It is an arithmetic number, because the mean of its divisors is an integer number (218320920).

Almost surely, 2^1291731897 is an apocalyptic number.

It is an amenable number.

1291731897 is a deficient number, since it is larger than the sum of its proper divisors (454835463).

1291731897 is an equidigital number, since it uses as much as digits as its factorization.

1291731897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6064543.

The product of its digits is 190512, while the sum is 48.

The square root of 1291731897 is about 35940.6719052385. The cubic root of 1291731897 is about 1089.0741786406.

The spelling of 1291731897 in words is "one billion, two hundred ninety-one million, seven hundred thirty-one thousand, eight hundred ninety-seven".