221356809 has 12 divisors (see below), whose sum is σ = 322256896. Its totient is φ = 146408472.

The previous prime is 221356801. The next prime is 221356823. The reversal of 221356809 is 908653122.

221356809 is a `hidden beast` number, since 221 + 356 + 80 + 9 = 666.

It is not a de Polignac number, because 221356809 - 2³ = 221356801 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (221356801) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 95689 + ... + 97974.

Almost surely, 2^221356809 is an apocalyptic number.

It is an amenable number.

221356809 is a deficient number, since it is larger than the sum of its proper divisors (100900087).

221356809 is a wasteful number, since it uses less digits than its factorization.

221356809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193796 (or 193793 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 221356809 is about 14878.0646926944. The cubic root of 221356809 is about 604.9195612839.

The spelling of 221356809 in words is "two hundred twenty-one million, three hundred fifty-six thousand, eight hundred nine".