166445421 has 4 divisors (see below), whose sum is σ = 221927232. Its totient is φ = 110963612.

The previous prime is 166445381. The next prime is 166445437. The reversal of 166445421 is 124544661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 124544661 = 3 ⋅41514887.

It is a cyclic number.

It is not a de Polignac number, because 166445421 - 2²¹ = 164348269 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166445441) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27740901 + ... + 27740906.

It is an arithmetic number, because the mean of its divisors is an integer number (55481808).

Almost surely, 2^166445421 is an apocalyptic number.

It is an amenable number.

166445421 is a deficient number, since it is larger than the sum of its proper divisors (55481811).

166445421 is an equidigital number, since it uses as much as digits as its factorization.

166445421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55481810.

The product of its digits is 23040, while the sum is 33.

The square root of 166445421 is about 12901.3728339274. The cubic root of 166445421 is about 550.0775879523.

The spelling of 166445421 in words is "one hundred sixty-six million, four hundred forty-five thousand, four hundred twenty-one".