1287931 has 4 divisors (see below), whose sum is σ = 1343952. Its totient is φ = 1231912.

The previous prime is 1287917. The next prime is 1287947. The reversal of 1287931 is 1397821.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1287931 - 2⁵ = 1287899 is a prime.

It is a super-2 number, since 2×1287931² = 3317532521522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1287893 and 1287902.

It is not an unprimeable number, because it can be changed into a prime (1287961) 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, 27976 + ... + 28021.

It is an arithmetic number, because the mean of its divisors is an integer number (335988).

2^1287931 is an apocalyptic number.

1287931 is a deficient number, since it is larger than the sum of its proper divisors (56021).

1287931 is an equidigital number, since it uses as much as digits as its factorization.

1287931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56020.

The product of its digits is 3024, while the sum is 31.

The square root of 1287931 is about 1134.8704771911. The cubic root of 1287931 is about 108.8004935729.

The spelling of 1287931 in words is "one million, two hundred eighty-seven thousand, nine hundred thirty-one".