1265318816520 has 256 divisors, whose sum is σ = 4204058112000. Its totient is φ = 302095872000.

The previous prime is 1265318816479. The next prime is 1265318816521. The reversal of 1265318816520 is 256188135621.

It is a self number, because there is not a number n which added to its sum of digits gives 1265318816520.

It is not an unprimeable number, because it can be changed into a prime (1265318816521) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 41801151 + ... + 41831409.

It is an arithmetic number, because the mean of its divisors is an integer number (16422102000).

Almost surely, 2^{1265318816520} is an apocalyptic number.

1265318816520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1265318816520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2102029056000).

1265318816520 is an abundant number, since it is smaller than the sum of its proper divisors (2938739295480).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1265318816520 is a wasteful number, since it uses less digits than its factorization.

1265318816520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30764 (or 30760 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 48.

The spelling of 1265318816520 in words is "one trillion, two hundred sixty-five billion, three hundred eighteen million, eight hundred sixteen thousand, five hundred twenty".