1265538891533 has 6 divisors (see below), whose sum is σ = 1472157486126. Its totient is φ = 1084747621272.

The previous prime is 1265538891499. The next prime is 1265538891571. The reversal of 1265538891533 is 3351988355621.

It can be written as a sum of positive squares in only one way, i.e., 1161917993929 + 103620897604 = 1077923^2 + 321902^2 .

It is not a de Polignac number, because 1265538891533 - 2⁶ = 1265538891469 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 (1265538891583) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12913662110 + ... + 12913662207.

It is an arithmetic number, because the mean of its divisors is an integer number (245359581021).

Almost surely, 2^{1265538891533} is an apocalyptic number.

It is an amenable number.

1265538891533 is a deficient number, since it is larger than the sum of its proper divisors (206618594593).

1265538891533 is an equidigital number, since it uses as much as digits as its factorization.

1265538891533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25827324331 (or 25827324324 counting only the distinct ones).

The product of its digits is 23328000, while the sum is 59.

The spelling of 1265538891533 in words is "one trillion, two hundred sixty-five billion, five hundred thirty-eight million, eight hundred ninety-one thousand, five hundred thirty-three".