1265861870 has 32 divisors (see below), whose sum is σ = 2804372928. Its totient is φ = 400624128.

The previous prime is 1265861791. The next prime is 1265861873. The reversal of 1265861870 is 781685621.

It is a happy number.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1265861873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 694619 + ... + 696438.

It is an arithmetic number, because the mean of its divisors is an integer number (87636654).

Almost surely, 2^1265861870 is an apocalyptic number.

1265861870 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1265861870 is an abundant number, since it is smaller than the sum of its proper divisors (1538511058).

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

1265861870 is a wasteful number, since it uses less digits than its factorization.

1265861870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1391084.

The product of its (nonzero) digits is 161280, while the sum is 44.

The square root of 1265861870 is about 35578.9526265178. The cubic root of 1265861870 is about 1081.7546551321.

The spelling of 1265861870 in words is "one billion, two hundred sixty-five million, eight hundred sixty-one thousand, eight hundred seventy".