1291865 has 4 divisors (see below), whose sum is σ = 1550244. Its totient is φ = 1033488.

The previous prime is 1291861. The next prime is 1291877. The reversal of 1291865 is 5681921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5681921 = 7 ⋅811703.

It can be written as a sum of positive squares in 2 ways, for example, as 425104 + 866761 = 652^2 + 931^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291865 - 2² = 1291861 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1291861) 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, 129182 + ... + 129191.

It is an arithmetic number, because the mean of its divisors is an integer number (387561).

2^1291865 is an apocalyptic number.

It is an amenable number.

1291865 is a deficient number, since it is larger than the sum of its proper divisors (258379).

1291865 is an equidigital number, since it uses as much as digits as its factorization.

1291865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258378.

The product of its digits is 4320, while the sum is 32.

The square root of 1291865 is about 1136.6023930997. The cubic root of 1291865 is about 108.9111584251.

The spelling of 1291865 in words is "one million, two hundred ninety-one thousand, eight hundred sixty-five".