1278091 has 4 divisors (see below), whose sum is σ = 1312672. Its totient is φ = 1243512.

The previous prime is 1278047. The next prime is 1278097. The reversal of 1278091 is 1908721.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1908721 = 19 ⋅100459.

It is a cyclic number.

It is not a de Polignac number, because 1278091 - 2¹⁹ = 753803 is a prime.

It is a Duffinian number.

1278091 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1278097) 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, 17235 + ... + 17308.

It is an arithmetic number, because the mean of its divisors is an integer number (328168).

2^1278091 is an apocalyptic number.

1278091 is a deficient number, since it is larger than the sum of its proper divisors (34581).

1278091 is an equidigital number, since it uses as much as digits as its factorization.

1278091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34580.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 1278091 is about 1130.5268683229. The cubic root of 1278091 is about 108.5227004822.

The spelling of 1278091 in words is "one million, two hundred seventy-eight thousand, ninety-one".