1265816800 has 144 divisors (see below), whose sum is σ = 3266790912. Its totient is φ = 478195200.

The previous prime is 1265816791. The next prime is 1265816801. The reversal of 1265816800 is 86185621.

It is a self number, because there is not a number n which added to its sum of digits gives 1265816800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1265816801) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1065807 + ... + 1066993.

It is an arithmetic number, because the mean of its divisors is an integer number (22686048).

Almost surely, 2^1265816800 is an apocalyptic number.

1265816800 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 1265816800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1633395456).

1265816800 is an abundant number, since it is smaller than the sum of its proper divisors (2000974112).

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

1265816800 is a wasteful number, since it uses less digits than its factorization.

1265816800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1281 (or 1268 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 1265816800 is about 35578.3192407961. The cubic root of 1265816800 is about 1081.7418166432.

The spelling of 1265816800 in words is "one billion, two hundred sixty-five million, eight hundred sixteen thousand, eight hundred".