1287389 has 4 divisors (see below), whose sum is σ = 1296924. Its totient is φ = 1277856.

The previous prime is 1287373. The next prime is 1287401. The reversal of 1287389 is 9837821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9837821 = 7 ⋅1405403.

It can be written as a sum of positive squares in 2 ways, for example, as 267289 + 1020100 = 517^2 + 1010^2 .

It is a cyclic number.

It is not a de Polignac number, because 1287389 - 2⁴ = 1287373 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 (1287329) 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, 4562 + ... + 4835.

It is an arithmetic number, because the mean of its divisors is an integer number (324231).

2^1287389 is an apocalyptic number.

It is an amenable number.

1287389 is a deficient number, since it is larger than the sum of its proper divisors (9535).

1287389 is an equidigital number, since it uses as much as digits as its factorization.

1287389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9534.

The product of its digits is 24192, while the sum is 38.

The square root of 1287389 is about 1134.6316582927. The cubic root of 1287389 is about 108.7852292610.

The spelling of 1287389 in words is "one million, two hundred eighty-seven thousand, three hundred eighty-nine".