166601221 has 8 divisors (see below), whose sum is σ = 171626400. Its totient is φ = 161628432.

The previous prime is 166601209. The next prime is 166601231. The reversal of 166601221 is 122106661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 166601221 - 2⁵ = 166601189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166601231) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6595 + ... + 19408.

It is an arithmetic number, because the mean of its divisors is an integer number (21453300).

Almost surely, 2^166601221 is an apocalyptic number.

It is an amenable number.

166601221 is a deficient number, since it is larger than the sum of its proper divisors (5025179).

166601221 is a wasteful number, since it uses less digits than its factorization.

166601221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26195.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 166601221 is about 12907.4095387107. The cubic root of 166601221 is about 550.2491664420.

Adding to 166601221 its reverse (122106661), we get a palindrome (288707882).

The spelling of 166601221 in words is "one hundred sixty-six million, six hundred one thousand, two hundred twenty-one".