166546621 has 2 divisors, whose sum is σ = 166546622. Its totient is φ = 166546620.

The previous prime is 166546619. The next prime is 166546631. The reversal of 166546621 is 126645661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 129640996 + 36905625 = 11386^2 + 6075^2 .

It is an emirp because it is prime and its reverse (126645661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166546621 - 2¹ = 166546619 is a prime.

Together with 166546619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166546631) 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 as a sum of consecutive naturals, namely, 83273310 + 83273311.

It is an arithmetic number, because the mean of its divisors is an integer number (83273311).

Almost surely, 2^166546621 is an apocalyptic number.

It is an amenable number.

166546621 is a deficient number, since it is larger than the sum of its proper divisors (1).

166546621 is an equidigital number, since it uses as much as digits as its factorization.

166546621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 37.

The square root of 166546621 is about 12905.2943011773. The cubic root of 166546621 is about 550.1890490611.

The spelling of 166546621 in words is "one hundred sixty-six million, five hundred forty-six thousand, six hundred twenty-one".