221664121 has 8 divisors (see below), whose sum is σ = 257624640. Its totient is φ = 186777168.

The previous prime is 221664119. The next prime is 221664161. The reversal of 221664121 is 121466122.

It is a happy number.

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 221664121 - 2¹ = 221664119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221664101) 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, 267946 + ... + 268771.

It is an arithmetic number, because the mean of its divisors is an integer number (32203080).

Almost surely, 2^221664121 is an apocalyptic number.

It is an amenable number.

221664121 is a deficient number, since it is larger than the sum of its proper divisors (35960519).

221664121 is an equidigital number, since it uses as much as digits as its factorization.

221664121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 536783.

The product of its digits is 1152, while the sum is 25.

The square root of 221664121 is about 14888.3887979862. The cubic root of 221664121 is about 605.1993705788.

The spelling of 221664121 in words is "two hundred twenty-one million, six hundred sixty-four thousand, one hundred twenty-one".