166221993 has 16 divisors (see below), whose sum is σ = 253532160. Its totient is φ = 94893456.

The previous prime is 166221941. The next prime is 166222009. The reversal of 166221993 is 399122661.

It is not a de Polignac number, because 166221993 - 2⁶ = 166221929 is a prime.

It is not an unprimeable number, because it can be changed into a prime (166221193) 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 in 15 ways as a sum of consecutive naturals, for example, 23296 + ... + 29582.

It is an arithmetic number, because the mean of its divisors is an integer number (15845760).

Almost surely, 2^166221993 is an apocalyptic number.

It is an amenable number.

166221993 is a deficient number, since it is larger than the sum of its proper divisors (87310167).

166221993 is a wasteful number, since it uses less digits than its factorization.

166221993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7556.

The product of its digits is 34992, while the sum is 39.

The square root of 166221993 is about 12892.7108476069. The cubic root of 166221993 is about 549.8313455335.

The spelling of 166221993 in words is "one hundred sixty-six million, two hundred twenty-one thousand, nine hundred ninety-three".