166531021 has 8 divisors (see below), whose sum is σ = 172753920. Its totient is φ = 160340208.

The previous prime is 166531019. The next prime is 166531033. The reversal of 166531021 is 120135661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 166531021 - 2¹ = 166531019 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 (166531051) 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 7 ways as a sum of consecutive naturals, for example, 2820 + ... + 18466.

It is an arithmetic number, because the mean of its divisors is an integer number (21594240).

Almost surely, 2^166531021 is an apocalyptic number.

It is an amenable number.

166531021 is a deficient number, since it is larger than the sum of its proper divisors (6222899).

166531021 is a wasteful number, since it uses less digits than its factorization.

166531021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16043.

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

The square root of 166531021 is about 12904.6898839143. The cubic root of 166531021 is about 550.1718702534.

Adding to 166531021 its reverse (120135661), we get a palindrome (286666682).

The spelling of 166531021 in words is "one hundred sixty-six million, five hundred thirty-one thousand, twenty-one".