221621172 has 12 divisors (see below), whose sum is σ = 517116096. Its totient is φ = 73873720.

The previous prime is 221621119. The next prime is 221621177. The reversal of 221621172 is 271126122.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221621177) 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, 9234204 + ... + 9234227.

It is an arithmetic number, because the mean of its divisors is an integer number (43093008).

Almost surely, 2^221621172 is an apocalyptic number.

It is an amenable number.

221621172 is an abundant number, since it is smaller than the sum of its proper divisors (295494924).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221621172 is a wasteful number, since it uses less digits than its factorization.

221621172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18468438 (or 18468436 counting only the distinct ones).

The product of its digits is 672, while the sum is 24.

The square root of 221621172 is about 14886.9463625016. The cubic root of 221621172 is about 605.1602808266.

Adding to 221621172 its reverse (271126122), we get a palindrome (492747294).

The spelling of 221621172 in words is "two hundred twenty-one million, six hundred twenty-one thousand, one hundred seventy-two".