1265891328 has 240 divisors, whose sum is σ = 4078914840. Its totient is φ = 388841472.

The previous prime is 1265891327. The next prime is 1265891329. The reversal of 1265891328 is 8231985621.

It is an interprime number because it is at equal distance from previous prime (1265891327) and next prime (1265891329).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1265891327) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2156251 + ... + 2156837.

Almost surely, 2^1265891328 is an apocalyptic number.

1265891328 is a gapful number since it is divisible by the number (18) 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 1265891328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2039457420).

1265891328 is an abundant number, since it is smaller than the sum of its proper divisors (2813023512).

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

1265891328 is an equidigital number, since it uses as much as digits as its factorization.

1265891328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 634 (or 605 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The square root of 1265891328 is about 35579.3666048175. The cubic root of 1265891328 is about 1081.7630462745.

The spelling of 1265891328 in words is "one billion, two hundred sixty-five million, eight hundred ninety-one thousand, three hundred twenty-eight".