1265904640 has 528 divisors, whose sum is σ = 4315403520. Its totient is φ = 345047040.

The previous prime is 1265904599. The next prime is 1265904641. The reversal of 1265904640 is 464095621.

It is a self number, because there is not a number n which added to its sum of digits gives 1265904640.

It is not an unprimeable number, because it can be changed into a prime (1265904641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 66626551 + ... + 66626569.

Almost surely, 2^1265904640 is an apocalyptic number.

1265904640 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 1265904640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2157701760).

1265904640 is an abundant number, since it is smaller than the sum of its proper divisors (3049498880).

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

1265904640 is a wasteful number, since it uses less digits than its factorization.

1265904640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88 (or 57 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 1265904640 is about 35579.5536790444. The cubic root of 1265904640 is about 1081.7668381690.

It can be divided in two parts, 126 and 5904640, that added together give a triangular number (5904766 = T₃₄₃₆).

The spelling of 1265904640 in words is "one billion, two hundred sixty-five million, nine hundred four thousand, six hundred forty".