1288781 has 4 divisors (see below), whose sum is σ = 1387932. Its totient is φ = 1189632.

The previous prime is 1288769. The next prime is 1288783. The reversal of 1288781 is 1878821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1878821 = 7 ⋅268403.

It can be written as a sum of positive squares in 2 ways, for example, as 111556 + 1177225 = 334^2 + 1085^2 .

It is a cyclic number.

It is not a de Polignac number, because 1288781 - 2¹⁰ = 1287757 is a prime.

It is a super-2 number, since 2×1288781² = 3321912931922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1288783) 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, 49556 + ... + 49581.

It is an arithmetic number, because the mean of its divisors is an integer number (346983).

2^1288781 is an apocalyptic number.

It is an amenable number.

1288781 is a deficient number, since it is larger than the sum of its proper divisors (99151).

1288781 is an equidigital number, since it uses as much as digits as its factorization.

1288781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99150.

The product of its digits is 7168, while the sum is 35.

The square root of 1288781 is about 1135.2449074979. The cubic root of 1288781 is about 108.8244234476.

The spelling of 1288781 in words is "one million, two hundred eighty-eight thousand, seven hundred eighty-one".