1261532765 has 16 divisors (see below), whose sum is σ = 1567707696. Its totient is φ = 973939200.

The previous prime is 1261532711. The next prime is 1261532771. The reversal of 1261532765 is 5672351621.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 264615289 + 996917476 = 16267^2 + 31574^2 .

It is not a de Polignac number, because 1261532765 - 2¹⁰ = 1261531741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 22856 + ... + 55185.

It is an arithmetic number, because the mean of its divisors is an integer number (97981731).

Almost surely, 2^1261532765 is an apocalyptic number.

It is an amenable number.

1261532765 is a deficient number, since it is larger than the sum of its proper divisors (306174931).

1261532765 is an equidigital number, since it uses as much as digits as its factorization.

1261532765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78160.

The product of its digits is 75600, while the sum is 38.

The square root of 1261532765 is about 35518.0625175417. The cubic root of 1261532765 is about 1080.5200870113.

The spelling of 1261532765 in words is "one billion, two hundred sixty-one million, five hundred thirty-two thousand, seven hundred sixty-five".