81265865 has 16 divisors (see below), whose sum is σ = 103598352. Its totient is φ = 60985344.

The previous prime is 81265861. The next prime is 81265879. The reversal of 81265865 is 56856218.

It can be written as a sum of positive squares in 8 ways, for example, as 9168784 + 72097081 = 3028^2 + 8491^2 .

It is a cyclic number.

It is not a de Polignac number, because 81265865 - 2² = 81265861 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81265861) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27227 + ... + 30063.

It is an arithmetic number, because the mean of its divisors is an integer number (6474897).

Almost surely, 2^81265865 is an apocalyptic number.

81265865 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81265865 is a deficient number, since it is larger than the sum of its proper divisors (22332487).

81265865 is a wasteful number, since it uses less digits than its factorization.

81265865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3196.

The product of its digits is 115200, while the sum is 41.

The square root of 81265865 is about 9014.7581775664. The cubic root of 81265865 is about 433.1477413659.

The spelling of 81265865 in words is "eighty-one million, two hundred sixty-five thousand, eight hundred sixty-five".