1280309 has 2 divisors, whose sum is σ = 1280310. Its totient is φ = 1280308.

The previous prime is 1280297. The next prime is 1280317. The reversal of 1280309 is 9030821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 908209 + 372100 = 953^2 + 610^2 .

It is a cyclic number.

It is not a de Polignac number, because 1280309 - 2¹² = 1276213 is a prime.

It is a super-2 number, since 2×1280309² = 3278382270962, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1280399) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 640154 + 640155.

It is an arithmetic number, because the mean of its divisors is an integer number (640155).

2^1280309 is an apocalyptic number.

It is an amenable number.

1280309 is a deficient number, since it is larger than the sum of its proper divisors (1).

1280309 is an equidigital number, since it uses as much as digits as its factorization.

1280309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 1280309 is about 1131.5074016550. The cubic root of 1280309 is about 108.5854409925.

The spelling of 1280309 in words is "one million, two hundred eighty thousand, three hundred nine".