66561610205166 has 64 divisors (see below), whose sum is σ = 141530110064640. Its totient is φ = 20796755640320.

The previous prime is 66561610205159. The next prime is 66561610205203. The reversal of 66561610205166 is 66150201616566.

It is a super-2 number, since 2×66561610205166² (a number of 28 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 135307075 + ... + 135798113.

It is an arithmetic number, because the mean of its divisors is an integer number (2211407969760).

Almost surely, 2^{66561610205166} is an apocalyptic number.

66561610205166 is an abundant number, since it is smaller than the sum of its proper divisors (74968499859474).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66561610205166 is a wasteful number, since it uses less digits than its factorization.

66561610205166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 496489.

The product of its (nonzero) digits is 2332800, while the sum is 51.

The spelling of 66561610205166 in words is "sixty-six trillion, five hundred sixty-one billion, six hundred ten million, two hundred five thousand, one hundred sixty-six".