221561664 has 28 divisors (see below), whose sum is σ = 586215744. Its totient is φ = 73853824.

The previous prime is 221561651. The next prime is 221561689. The reversal of 221561664 is 466165122.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 576792 + ... + 577175.

Almost surely, 2^221561664 is an apocalyptic number.

221561664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

221561664 is an abundant number, since it is smaller than the sum of its proper divisors (364654080).

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

221561664 is a wasteful number, since it uses less digits than its factorization.

221561664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1153982 (or 1153972 counting only the distinct ones).

The product of its digits is 17280, while the sum is 33.

The square root of 221561664 is about 14884.9475645701. The cubic root of 221561664 is about 605.1061116613.

The spelling of 221561664 in words is "two hundred twenty-one million, five hundred sixty-one thousand, six hundred sixty-four".