221678221 has 8 divisors (see below), whose sum is σ = 223432704. Its totient is φ = 219929520.

The previous prime is 221678203. The next prime is 221678227. The reversal of 221678221 is 122876122.

It is a happy number.

221678221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221678221 - 2⁵ = 221678189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221678227) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 103956 + ... + 106066.

It is an arithmetic number, because the mean of its divisors is an integer number (27929088).

Almost surely, 2^221678221 is an apocalyptic number.

It is an amenable number.

221678221 is a deficient number, since it is larger than the sum of its proper divisors (1754483).

221678221 is a wasteful number, since it uses less digits than its factorization.

221678221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2891.

The product of its digits is 5376, while the sum is 31.

The square root of 221678221 is about 14888.8623138237. The cubic root of 221678221 is about 605.2122025009.

The spelling of 221678221 in words is "two hundred twenty-one million, six hundred seventy-eight thousand, two hundred twenty-one".