166521313 has 4 divisors (see below), whose sum is σ = 190310080. Its totient is φ = 142732548.

The previous prime is 166521293. The next prime is 166521317. The reversal of 166521313 is 313125661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 166521313 - 2²⁵ = 132966881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166521317) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11894373 + ... + 11894386.

It is an arithmetic number, because the mean of its divisors is an integer number (47577520).

Almost surely, 2^166521313 is an apocalyptic number.

It is an amenable number.

166521313 is a deficient number, since it is larger than the sum of its proper divisors (23788767).

166521313 is an equidigital number, since it uses as much as digits as its factorization.

166521313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23788766.

The product of its digits is 3240, while the sum is 28.

The square root of 166521313 is about 12904.3137361117. The cubic root of 166521313 is about 550.1611792076.

Adding to 166521313 its reverse (313125661), we get a palindrome (479646974).

The spelling of 166521313 in words is "one hundred sixty-six million, five hundred twenty-one thousand, three hundred thirteen".