66561412165 has 8 divisors (see below), whose sum is σ = 79876523160. Its totient is φ = 53247244032.

The previous prime is 66561412133. The next prime is 66561412243. The reversal of 66561412165 is 56121416566.

It can be written as a sum of positive squares in 4 ways, for example, as 29325535009 + 37235877156 = 171247^2 + 192966^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66561412165 - 2⁵ = 66561412133 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69784 + ... + 371473.

It is an arithmetic number, because the mean of its divisors is an integer number (9984565395).

Almost surely, 2^66561412165 is an apocalyptic number.

It is an amenable number.

66561412165 is a deficient number, since it is larger than the sum of its proper divisors (13315110995).

66561412165 is a wasteful number, since it uses less digits than its factorization.

66561412165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 471431.

The product of its digits is 259200, while the sum is 43.

The spelling of 66561412165 in words is "sixty-six billion, five hundred sixty-one million, four hundred twelve thousand, one hundred sixty-five".