1287241561 has 4 divisors (see below), whose sum is σ = 1287668452. Its totient is φ = 1286814672.

The previous prime is 1287241559. The next prime is 1287241567. The reversal of 1287241561 is 1651427821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1651427821 = 17 ⋅97142813.

It can be written as a sum of positive squares in 2 ways, for example, as 1128960000 + 158281561 = 33600^2 + 12581^2 .

It is a cyclic number.

It is not a de Polignac number, because 1287241561 - 2¹ = 1287241559 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1287241561.

It is not an unprimeable number, because it can be changed into a prime (1287241567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 208890 + ... + 214963.

It is an arithmetic number, because the mean of its divisors is an integer number (321917113).

Almost surely, 2^1287241561 is an apocalyptic number.

It is an amenable number.

1287241561 is a deficient number, since it is larger than the sum of its proper divisors (426891).

1287241561 is an equidigital number, since it uses as much as digits as its factorization.

1287241561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 426890.

The product of its digits is 26880, while the sum is 37.

The square root of 1287241561 is about 35878.1487956110. The cubic root of 1287241561 is about 1087.8107620453.

The spelling of 1287241561 in words is "one billion, two hundred eighty-seven million, two hundred forty-one thousand, five hundred sixty-one".