166501661 has 4 divisors (see below), whose sum is σ = 166955712. Its totient is φ = 166047612.

The previous prime is 166501649. The next prime is 166501667. The reversal of 166501661 is 166105661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 166501661 - 2⁶ = 166501597 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166501667) 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, 226475 + ... + 227208.

It is an arithmetic number, because the mean of its divisors is an integer number (41738928).

Almost surely, 2^166501661 is an apocalyptic number.

It is an amenable number.

166501661 is a deficient number, since it is larger than the sum of its proper divisors (454051).

166501661 is an equidigital number, since it uses as much as digits as its factorization.

166501661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 454050.

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 166501661 is about 12903.5522628461. The cubic root of 166501661 is about 550.1395359464.

The spelling of 166501661 in words is "one hundred sixty-six million, five hundred one thousand, six hundred sixty-one".