221661204 has 12 divisors (see below), whose sum is σ = 517209504. Its totient is φ = 73887064.

The previous prime is 221661169. The next prime is 221661257. The reversal of 221661204 is 402166122.

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

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, 9235872 + ... + 9235895.

It is an arithmetic number, because the mean of its divisors is an integer number (43100792).

Almost surely, 2^221661204 is an apocalyptic number.

It is an amenable number.

221661204 is an abundant number, since it is smaller than the sum of its proper divisors (295548300).

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

221661204 is a wasteful number, since it uses less digits than its factorization.

221661204 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18471774 (or 18471772 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 221661204 is about 14888.2908354183. The cubic root of 221661204 is about 605.1967158501.

The spelling of 221661204 in words is "two hundred twenty-one million, six hundred sixty-one thousand, two hundred four".