66871265765 has 4 divisors (see below), whose sum is σ = 80245518924. Its totient is φ = 53497012608.

The previous prime is 66871265761. The next prime is 66871265771. The reversal of 66871265765 is 56756217866.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 38115924289 + 28755341476 = 195233^2 + 169574^2 .

It is a cyclic number.

It is not a de Polignac number, because 66871265765 - 2² = 66871265761 is a prime.

It is a super-2 number, since 2×66871265765² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66871265761) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6687126572 + ... + 6687126581.

It is an arithmetic number, because the mean of its divisors is an integer number (20061379731).

Almost surely, 2^66871265765 is an apocalyptic number.

It is an amenable number.

66871265765 is a deficient number, since it is larger than the sum of its proper divisors (13374253159).

66871265765 is a wasteful number, since it uses less digits than its factorization.

66871265765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13374253158.

The product of its digits is 25401600, while the sum is 59.

The spelling of 66871265765 in words is "sixty-six billion, eight hundred seventy-one million, two hundred sixty-five thousand, seven hundred sixty-five".