1287598261 has 4 divisors (see below), whose sum is σ = 1322398252. Its totient is φ = 1252798272.

The previous prime is 1287598201. The next prime is 1287598267. The reversal of 1287598261 is 1628957821.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1143454225 + 144144036 = 33815^2 + 12006^2 .

It is a cyclic number.

It is not a de Polignac number, because 1287598261 - 2⁷ = 1287598133 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 (1287598267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17399940 + ... + 17400013.

It is an arithmetic number, because the mean of its divisors is an integer number (330599563).

Almost surely, 2^1287598261 is an apocalyptic number.

It is an amenable number.

1287598261 is a deficient number, since it is larger than the sum of its proper divisors (34799991).

1287598261 is an equidigital number, since it uses as much as digits as its factorization.

1287598261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34799990.

The product of its digits is 483840, while the sum is 49.

The square root of 1287598261 is about 35883.1194435489. The cubic root of 1287598261 is about 1087.9112317306.

The spelling of 1287598261 in words is "one billion, two hundred eighty-seven million, five hundred ninety-eight thousand, two hundred sixty-one".