166651 has 4 divisors (see below), whose sum is σ = 176472. Its totient is φ = 156832.

The previous prime is 166643. The next prime is 166657. The reversal of 166651 is 156661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 156661 = 41 ⋅3821.

It is a cyclic number.

It is not a de Polignac number, because 166651 - 2³ = 166643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4885 + ... + 4918.

It is an arithmetic number, because the mean of its divisors is an integer number (44118).

2¹⁶⁶⁶⁵¹ is an apocalyptic number.

166651 is a deficient number, since it is larger than the sum of its proper divisors (9821).

166651 is an equidigital number, since it uses as much as digits as its factorization.

166651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9820.

The product of its digits is 1080, while the sum is 25.

The square root of 166651 is about 408.2291023433. The cubic root of 166651 is about 55.0303964211.

The spelling of 166651 in words is "one hundred sixty-six thousand, six hundred fifty-one".