1265985280 has 144 divisors (see below), whose sum is σ = 3486409920. Its totient is φ = 431456256.

The previous prime is 1265985271. The next prime is 1265985289. The reversal of 1265985280 is 825895621.

It is an interprime number because it is at equal distance from previous prime (1265985271) and next prime (1265985289).

It is a self number, because there is not a number n which added to its sum of digits gives 1265985280.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1265985289) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2051532 + ... + 2052148.

It is an arithmetic number, because the mean of its divisors is an integer number (24211180).

Almost surely, 2^1265985280 is an apocalyptic number.

1265985280 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 1265985280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1743204960).

1265985280 is an abundant number, since it is smaller than the sum of its proper divisors (2220424640).

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

1265985280 is an equidigital number, since it uses as much as digits as its factorization.

1265985280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 874 (or 860 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 46.

The square root of 1265985280 is about 35580.6868961239. The cubic root of 1265985280 is about 1081.7898077311.

The spelling of 1265985280 in words is "one billion, two hundred sixty-five million, nine hundred eighty-five thousand, two hundred eighty".