1278649 has 4 divisors (see below), whose sum is σ = 1282036. Its totient is φ = 1275264.

The previous prime is 1278637. The next prime is 1278659. The reversal of 1278649 is 9468721.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9468721 = 109 ⋅86869.

It can be written as a sum of positive squares in 2 ways, for example, as 573049 + 705600 = 757^2 + 840^2 .

It is a cyclic number.

It is not a de Polignac number, because 1278649 - 2⁵ = 1278617 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 (1278619) 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, 1044 + ... + 1909.

It is an arithmetic number, because the mean of its divisors is an integer number (320509).

2^1278649 is an apocalyptic number.

It is an amenable number.

1278649 is a deficient number, since it is larger than the sum of its proper divisors (3387).

1278649 is an equidigital number, since it uses as much as digits as its factorization.

1278649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3386.

The product of its digits is 24192, while the sum is 37.

The square root of 1278649 is about 1130.7736289815. The cubic root of 1278649 is about 108.5384914434.

The spelling of 1278649 in words is "one million, two hundred seventy-eight thousand, six hundred forty-nine".