1280605 has 4 divisors (see below), whose sum is σ = 1536732. Its totient is φ = 1024480.

The previous prime is 1280603. The next prime is 1280623. The reversal of 1280605 is 5060821.

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: 5060821 = 19 ⋅266359.

It can be written as a sum of positive squares in 2 ways, for example, as 502681 + 777924 = 709^2 + 882^2 .

It is not a de Polignac number, because 1280605 - 2¹ = 1280603 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1280603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 128056 + ... + 128065.

It is an arithmetic number, because the mean of its divisors is an integer number (384183).

2^1280605 is an apocalyptic number.

It is an amenable number.

1280605 is a deficient number, since it is larger than the sum of its proper divisors (256127).

1280605 is an equidigital number, since it uses as much as digits as its factorization.

1280605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256126.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 1280605 is about 1131.6381930635. The cubic root of 1280605 is about 108.5938084554.

It can be divided in two parts, 1280 and 605, that multiplied together give a square (774400 = 880²).

The spelling of 1280605 in words is "one million, two hundred eighty thousand, six hundred five".