166042321 has 2 divisors, whose sum is σ = 166042322. Its totient is φ = 166042320.

The previous prime is 166042309. The next prime is 166042337. The reversal of 166042321 is 123240661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 89567296 + 76475025 = 9464^2 + 8745^2 .

It is a cyclic number.

It is not a de Polignac number, because 166042321 - 2¹³ = 166034129 is a prime.

It is a super-3 number, since 3×166042321³ (a number of 26 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (166042351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83021160 + 83021161.

It is an arithmetic number, because the mean of its divisors is an integer number (83021161).

Almost surely, 2^166042321 is an apocalyptic number.

It is an amenable number.

166042321 is a deficient number, since it is larger than the sum of its proper divisors (1).

166042321 is an equidigital number, since it uses as much as digits as its factorization.

166042321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 166042321 is about 12885.7409953793. The cubic root of 166042321 is about 549.6331669583.

Adding to 166042321 its reverse (123240661), we get a palindrome (289282982).

The spelling of 166042321 in words is "one hundred sixty-six million, forty-two thousand, three hundred twenty-one".