166331021 has 8 divisors (see below), whose sum is σ = 171453720. Its totient is φ = 161241408.

The previous prime is 166330999. The next prime is 166331029. The reversal of 166331021 is 120133661.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 78234025 + 88096996 = 8845^2 + 9386^2 .

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 166331021 - 2¹⁴ = 166314637 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 (166331029) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2135 + ... + 18363.

It is an arithmetic number, because the mean of its divisors is an integer number (21431715).

Almost surely, 2^166331021 is an apocalyptic number.

It is an amenable number.

166331021 is a deficient number, since it is larger than the sum of its proper divisors (5122699).

166331021 is a wasteful number, since it uses less digits than its factorization.

166331021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16543.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 166331021 is about 12896.9384351481. The cubic root of 166331021 is about 549.9515340213.

Adding to 166331021 its reverse (120133661), we get a palindrome (286464682).

The spelling of 166331021 in words is "one hundred sixty-six million, three hundred thirty-one thousand, twenty-one".