1256261565 has 16 divisors (see below), whose sum is σ = 2164635648. Its totient is φ = 618467136.

The previous prime is 1256261549. The next prime is 1256261581. The reversal of 1256261565 is 5651626521.

It is a happy number.

1256261565 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (1256261549) and next prime (1256261581).

It is not a de Polignac number, because 1256261565 - 2⁴ = 1256261549 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3220989 + ... + 3221378.

It is an arithmetic number, because the mean of its divisors is an integer number (135289728).

Almost surely, 2^1256261565 is an apocalyptic number.

1256261565 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1256261565 is a deficient number, since it is larger than the sum of its proper divisors (908374083).

1256261565 is a wasteful number, since it uses less digits than its factorization.

1256261565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6442388.

The product of its digits is 108000, while the sum is 39.

The square root of 1256261565 is about 35443.7803429600. The cubic root of 1256261565 is about 1079.0130343718.

The spelling of 1256261565 in words is "one billion, two hundred fifty-six million, two hundred sixty-one thousand, five hundred sixty-five".