166621289 has 2 divisors, whose sum is σ = 166621290. Its totient is φ = 166621288.

The previous prime is 166621237. The next prime is 166621291. The reversal of 166621289 is 982126661.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 123587689 + 43033600 = 11117^2 + 6560^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166621289 is a prime.

Together with 166621291, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (166621219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83310644 + 83310645.

It is an arithmetic number, because the mean of its divisors is an integer number (83310645).

Almost surely, 2^166621289 is an apocalyptic number.

It is an amenable number.

166621289 is a deficient number, since it is larger than the sum of its proper divisors (1).

166621289 is an equidigital number, since it uses as much as digits as its factorization.

166621289 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 41.

The square root of 166621289 is about 12908.1868982441. The cubic root of 166621289 is about 550.2712590310.

The spelling of 166621289 in words is "one hundred sixty-six million, six hundred twenty-one thousand, two hundred eighty-nine".