221521464 has 48 divisors (see below), whose sum is σ = 626043600. Its totient is φ = 70629504.

The previous prime is 221521453. The next prime is 221521477. The reversal of 221521464 is 464125122.

221521464 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 65229 + ... + 68540.

It is an arithmetic number, because the mean of its divisors is an integer number (13042575).

Almost surely, 2^221521464 is an apocalyptic number.

221521464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

221521464 is an abundant number, since it is smaller than the sum of its proper divisors (404522136).

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

221521464 is a wasteful number, since it uses less digits than its factorization.

221521464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133804 (or 133797 counting only the distinct ones).

The product of its digits is 3840, while the sum is 27.

The square root of 221521464 is about 14883.5971458515. The cubic root of 221521464 is about 605.0695127651.

Adding to 221521464 its reverse (464125122), we get a palindrome (685646586).

The spelling of 221521464 in words is "two hundred twenty-one million, five hundred twenty-one thousand, four hundred sixty-four".