166145521 has 4 divisors (see below), whose sum is σ = 166179700. Its totient is φ = 166111344.

The previous prime is 166145477. The next prime is 166145527. The reversal of 166145521 is 125541661.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 40144896 + 126000625 = 6336^2 + 11225^2 .

It is a cyclic number.

It is not a de Polignac number, because 166145521 - 2⁹ = 166145009 is a prime.

It is a super-2 number, since 2×166145521² = 55208668296722882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166145527) 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 3 ways as a sum of consecutive naturals, for example, 8286 + ... + 20023.

It is an arithmetic number, because the mean of its divisors is an integer number (41544925).

Almost surely, 2^166145521 is an apocalyptic number.

It is an amenable number.

166145521 is a deficient number, since it is larger than the sum of its proper divisors (34179).

166145521 is an equidigital number, since it uses as much as digits as its factorization.

166145521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34178.

The product of its digits is 7200, while the sum is 31.

The square root of 166145521 is about 12889.7447996460. The cubic root of 166145521 is about 549.7470142294.

The spelling of 166145521 in words is "one hundred sixty-six million, one hundred forty-five thousand, five hundred twenty-one".