1261876765 has 12 divisors (see below), whose sum is σ = 1603742004. Its totient is φ = 949872384.

The previous prime is 1261876747. The next prime is 1261876769. The reversal of 1261876765 is 5676781621.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 605799769 + 656076996 = 24613^2 + 25614^2 .

It is not a de Polignac number, because 1261876765 - 2²¹ = 1259779613 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 (1261876769) 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 11 ways as a sum of consecutive naturals, for example, 325579 + ... + 329431.

It is an arithmetic number, because the mean of its divisors is an integer number (133645167).

Almost surely, 2^1261876765 is an apocalyptic number.

It is an amenable number.

1261876765 is a deficient number, since it is larger than the sum of its proper divisors (341865239).

1261876765 is an frugal number, since it uses more digits than its factorization.

1261876765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7728 (or 3875 counting only the distinct ones).

The product of its digits is 846720, while the sum is 49.

The square root of 1261876765 is about 35522.9047939495. The cubic root of 1261876765 is about 1080.6182916557.

The spelling of 1261876765 in words is "one billion, two hundred sixty-one million, eight hundred seventy-six thousand, seven hundred sixty-five".