166505661 has 48 divisors (see below), whose sum is σ = 287168128. Its totient is φ = 90979200.

The previous prime is 166505639. The next prime is 166505663.

166505661 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 166505661 - 2⁵ = 166505629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166505663) 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 47 ways as a sum of consecutive naturals, for example, 141606 + ... + 142776.

Almost surely, 2^166505661 is an apocalyptic number.

It is an amenable number.

166505661 is a deficient number, since it is larger than the sum of its proper divisors (120662467).

166505661 is a wasteful number, since it uses less digits than its factorization.

166505661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1282 (or 1279 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

The square root of 166505661 is about 12903.7072579937. The cubic root of 166505661 is about 550.1439413889.

The spelling of 166505661 in words is "one hundred sixty-six million, five hundred five thousand, six hundred sixty-one".