166221225 has 36 divisors (see below), whose sum is σ = 307337472. Its totient is φ = 85788000.

The previous prime is 166221221. The next prime is 166221227. The reversal of 166221225 is 522122661.

166221225 is a `hidden beast` number, since 1 + 6 + 622 + 12 + 25 = 666.

166221225 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 166221225 - 2² = 166221221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166221221) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 4941 + ... + 18890.

It is an arithmetic number, because the mean of its divisors is an integer number (8537152).

Almost surely, 2^166221225 is an apocalyptic number.

166221225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

166221225 is a deficient number, since it is larger than the sum of its proper divisors (141116247).

166221225 is a wasteful number, since it uses less digits than its factorization.

166221225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23878 (or 23870 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 166221225 is about 12892.6810633010. The cubic root of 166221225 is about 549.8304987320.

Adding to 166221225 its reverse (522122661), we get a palindrome (688343886).

The spelling of 166221225 in words is "one hundred sixty-six million, two hundred twenty-one thousand, two hundred twenty-five".