66642161 has 4 divisors (see below), whose sum is σ = 66733812. Its totient is φ = 66550512.

The previous prime is 66642151. The next prime is 66642167. The reversal of 66642161 is 16124666.

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 58232161 + 8410000 = 7631^2 + 2900^2 .

It is a cyclic number.

It is not a de Polignac number, because 66642161 - 2¹⁰ = 66641137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66642167) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44726 + ... + 46191.

It is an arithmetic number, because the mean of its divisors is an integer number (16683453).

Almost surely, 2^66642161 is an apocalyptic number.

It is an amenable number.

66642161 is a deficient number, since it is larger than the sum of its proper divisors (91651).

66642161 is an equidigital number, since it uses as much as digits as its factorization.

66642161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91650.

The product of its digits is 10368, while the sum is 32.

The square root of 66642161 is about 8163.4650118684. The cubic root of 66642161 is about 405.4304441445.

The spelling of 66642161 in words is "sixty-six million, six hundred forty-two thousand, one hundred sixty-one".