166821313 has 2 divisors, whose sum is σ = 166821314. Its totient is φ = 166821312.

The previous prime is 166821269. The next prime is 166821329. The reversal of 166821313 is 313128661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 158936449 + 7884864 = 12607^2 + 2808^2 .

It is a cyclic number.

It is not a de Polignac number, because 166821313 - 2¹⁷ = 166690241 is a prime.

It is not a weakly prime, because it can be changed into another prime (166821353) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83410656 + 83410657.

It is an arithmetic number, because the mean of its divisors is an integer number (83410657).

Almost surely, 2^166821313 is an apocalyptic number.

It is an amenable number.

166821313 is a deficient number, since it is larger than the sum of its proper divisors (1).

166821313 is an equidigital number, since it uses as much as digits as its factorization.

166821313 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 31.

The square root of 166821313 is about 12915.9325253735. The cubic root of 166821313 is about 550.4913658454.

Adding to 166821313 its reverse (313128661), we get a palindrome (479949974).

The spelling of 166821313 in words is "one hundred sixty-six million, eight hundred twenty-one thousand, three hundred thirteen".