66626838865 has 4 divisors (see below), whose sum is σ = 79952206644. Its totient is φ = 53301471088.

The previous prime is 66626838857. The next prime is 66626838881. The reversal of 66626838865 is 56883862666.

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 18564607504 + 48062231361 = 136252^2 + 219231^2 .

It is a cyclic number.

It is not a de Polignac number, because 66626838865 - 2³ = 66626838857 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66626838797 and 66626838806.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6662683882 + ... + 6662683891.

It is an arithmetic number, because the mean of its divisors is an integer number (19988051661).

Almost surely, 2^66626838865 is an apocalyptic number.

It is an amenable number.

66626838865 is a deficient number, since it is larger than the sum of its proper divisors (13325367779).

66626838865 is a wasteful number, since it uses less digits than its factorization.

66626838865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13325367778.

The product of its digits is 119439360, while the sum is 64.

The spelling of 66626838865 in words is "sixty-six billion, six hundred twenty-six million, eight hundred thirty-eight thousand, eight hundred sixty-five".