166421 has 6 divisors (see below), whose sum is σ = 176022. Its totient is φ = 157320.

The previous prime is 166417. The next prime is 166429. The reversal of 166421 is 124661.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 130321 + 36100 = 361^2 + 190^2 .

It is not a de Polignac number, because 166421 - 2² = 166417 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 166393 and 166402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 131 + ... + 591.

It is an arithmetic number, because the mean of its divisors is an integer number (29337).

2¹⁶⁶⁴²¹ is an apocalyptic number.

It is an amenable number.

166421 is a deficient number, since it is larger than the sum of its proper divisors (9601).

166421 is an equidigital number, since it uses as much as digits as its factorization.

166421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 499 (or 480 counting only the distinct ones).

The product of its digits is 288, while the sum is 20.

The square root of 166421 is about 407.9473005181. The cubic root of 166421 is about 55.0050684034.

The spelling of 166421 in words is "one hundred sixty-six thousand, four hundred twenty-one".