1256265640 has 128 divisors (see below), whose sum is σ = 3332229120. Its totient is φ = 417312000.

The previous prime is 1256265599. The next prime is 1256265641. The reversal of 1256265640 is 465626521.

It is a self number, because there is not a number n which added to its sum of digits gives 1256265640.

It is not an unprimeable number, because it can be changed into a prime (1256265641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1817695 + ... + 1818385.

It is an arithmetic number, because the mean of its divisors is an integer number (26033040).

Almost surely, 2^1256265640 is an apocalyptic number.

1256265640 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 1256265640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1666114560).

1256265640 is an abundant number, since it is smaller than the sum of its proper divisors (2075963480).

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

1256265640 is a wasteful number, since it uses less digits than its factorization.

1256265640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 903 (or 899 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 37.

The square root of 1256265640 is about 35443.8378283165. The cubic root of 1256265640 is about 1079.0142010538.

It can be divided in two parts, 1256265 and 640, that added together give a triangular number (1256905 = T₁₅₈₅).

The spelling of 1256265640 in words is "one billion, two hundred fifty-six million, two hundred sixty-five thousand, six hundred forty".