1287078761 has 4 divisors (see below), whose sum is σ = 1288915524. Its totient is φ = 1285242000.

The previous prime is 1287078757. The next prime is 1287078763. The reversal of 1287078761 is 1678707821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1678707821 = 7 ⋅239815403.

It can be written as a sum of positive squares in 2 ways, for example, as 1239040000 + 48038761 = 35200^2 + 6931^2 .

It is a cyclic number.

It is not a de Polignac number, because 1287078761 - 2² = 1287078757 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1287078763) 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, 917330 + ... + 918731.

It is an arithmetic number, because the mean of its divisors is an integer number (322228881).

Almost surely, 2^1287078761 is an apocalyptic number.

It is an amenable number.

1287078761 is a deficient number, since it is larger than the sum of its proper divisors (1836763).

1287078761 is an equidigital number, since it uses as much as digits as its factorization.

1287078761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1836762.

The product of its (nonzero) digits is 263424, while the sum is 47.

The square root of 1287078761 is about 35875.8799334595. The cubic root of 1287078761 is about 1087.7649009151.

The spelling of 1287078761 in words is "one billion, two hundred eighty-seven million, seventy-eight thousand, seven hundred sixty-one".