166721077 has 2 divisors, whose sum is σ = 166721078. Its totient is φ = 166721076.

The previous prime is 166721011. The next prime is 166721081. The reversal of 166721077 is 770127661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 158734801 + 7986276 = 12599^2 + 2826^2 .

It is an emirp because it is prime and its reverse (770127661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166721077 - 2¹⁵ = 166688309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166721777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83360538 + 83360539.

It is an arithmetic number, because the mean of its divisors is an integer number (83360539).

Almost surely, 2^166721077 is an apocalyptic number.

It is an amenable number.

166721077 is a deficient number, since it is larger than the sum of its proper divisors (1).

166721077 is an equidigital number, since it uses as much as digits as its factorization.

166721077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24696, while the sum is 37.

The square root of 166721077 is about 12912.0516185461. The cubic root of 166721077 is about 550.3810879542.

The spelling of 166721077 in words is "one hundred sixty-six million, seven hundred twenty-one thousand, seventy-seven".