1265816916321 has 8 divisors (see below), whose sum is σ = 1692854850144. Its totient is φ = 841328463360.

The previous prime is 1265816916293. The next prime is 1265816916341. The reversal of 1265816916321 is 1236196185621.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1265816916321 - 2⁶ = 1265816916257 is a prime.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (1265816916341) 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 7 ways as a sum of consecutive naturals, for example, 637369056 + ... + 637371041.

It is an arithmetic number, because the mean of its divisors is an integer number (211606856268).

Almost surely, 2^{1265816916321} is an apocalyptic number.

It is an amenable number.

1265816916321 is a deficient number, since it is larger than the sum of its proper divisors (427037933823).

1265816916321 is a wasteful number, since it uses less digits than its factorization.

1265816916321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1274740431.

The product of its digits is 933120, while the sum is 51.

The spelling of 1265816916321 in words is "one trillion, two hundred sixty-five billion, eight hundred sixteen million, nine hundred sixteen thousand, three hundred twenty-one".