1278285391 has 4 divisors (see below), whose sum is σ = 1290941784. Its totient is φ = 1265629000.

The previous prime is 1278285389. The next prime is 1278285419. The reversal of 1278285391 is 1935828721.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1935828721 = 101 ⋅19166621.

It is a cyclic number.

It is not a de Polignac number, because 1278285391 - 2¹ = 1278285389 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 (1278280391) 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, 6328045 + ... + 6328246.

It is an arithmetic number, because the mean of its divisors is an integer number (322735446).

Almost surely, 2^1278285391 is an apocalyptic number.

1278285391 is a deficient number, since it is larger than the sum of its proper divisors (12656393).

1278285391 is a wasteful number, since it uses less digits than its factorization.

1278285391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12656392.

The product of its digits is 241920, while the sum is 46.

The square root of 1278285391 is about 35753.1172207403. The cubic root of 1278285391 is about 1085.2820211622.

The spelling of 1278285391 in words is "one billion, two hundred seventy-eight million, two hundred eighty-five thousand, three hundred ninety-one".