66100506565 has 4 divisors (see below), whose sum is σ = 79320607884. Its totient is φ = 52880405248.

The previous prime is 66100506559. The next prime is 66100506583. The reversal of 66100506565 is 56560500166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56560500166 = 2 ⋅28280250083.

It can be written as a sum of positive squares in 2 ways, for example, as 8700971841 + 57399534724 = 93279^2 + 239582^2 .

It is a cyclic number.

It is not a de Polignac number, because 66100506565 - 2⁵ = 66100506533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6610050652 + ... + 6610050661.

It is an arithmetic number, because the mean of its divisors is an integer number (19830151971).

Almost surely, 2^66100506565 is an apocalyptic number.

It is an amenable number.

66100506565 is a deficient number, since it is larger than the sum of its proper divisors (13220101319).

66100506565 is a wasteful number, since it uses less digits than its factorization.

66100506565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13220101318.

The product of its (nonzero) digits is 162000, while the sum is 40.

The spelling of 66100506565 in words is "sixty-six billion, one hundred million, five hundred six thousand, five hundred sixty-five".