166864421 has 2 divisors, whose sum is σ = 166864422. Its totient is φ = 166864420.

The previous prime is 166864391. The next prime is 166864427. The reversal of 166864421 is 124468661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 166771396 + 93025 = 12914^2 + 305^2 .

It is a cyclic number.

It is not a de Polignac number, because 166864421 - 2¹⁴ = 166848037 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166864427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83432210 + 83432211.

It is an arithmetic number, because the mean of its divisors is an integer number (83432211).

Almost surely, 2^166864421 is an apocalyptic number.

It is an amenable number.

166864421 is a deficient number, since it is larger than the sum of its proper divisors (1).

166864421 is an equidigital number, since it uses as much as digits as its factorization.

166864421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 55296, while the sum is 38.

The square root of 166864421 is about 12917.6012092029. The cubic root of 166864421 is about 550.5387789279.

The spelling of 166864421 in words is "one hundred sixty-six million, eight hundred sixty-four thousand, four hundred twenty-one".