166565565651 has 4 divisors (see below), whose sum is σ = 222087420872. Its totient is φ = 111043710432.

The previous prime is 166565565641. The next prime is 166565565659. The reversal of 166565565651 is 156565565661.

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

It is a de Polignac number, because none of the positive numbers 2^k-166565565651 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 166565565591 and 166565565600.

It is not an unprimeable number, because it can be changed into a prime (166565565659) 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 3 ways as a sum of consecutive naturals, for example, 27760927606 + ... + 27760927611.

It is an arithmetic number, because the mean of its divisors is an integer number (55521855218).

Almost surely, 2^166565565651 is an apocalyptic number.

166565565651 is a deficient number, since it is larger than the sum of its proper divisors (55521855221).

166565565651 is an equidigital number, since it uses as much as digits as its factorization.

166565565651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55521855220.

The product of its digits is 24300000, while the sum is 57.

The spelling of 166565565651 in words is "one hundred sixty-six billion, five hundred sixty-five million, five hundred sixty-five thousand, six hundred fifty-one".