221856729 has 8 divisors (see below), whose sum is σ = 296516640. Its totient is φ = 147550656.

The previous prime is 221856683. The next prime is 221856731. The reversal of 221856729 is 927658122.

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

It is not a de Polignac number, because 221856729 - 2⁷ = 221856601 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221856799) 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, 86992 + ... + 89505.

It is an arithmetic number, because the mean of its divisors is an integer number (37064580).

Almost surely, 2^221856729 is an apocalyptic number.

It is an amenable number.

221856729 is a deficient number, since it is larger than the sum of its proper divisors (74659911).

221856729 is a wasteful number, since it uses less digits than its factorization.

221856729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176919.

The product of its digits is 120960, while the sum is 42.

The square root of 221856729 is about 14894.8557898356. The cubic root of 221856729 is about 605.3746094251.

The spelling of 221856729 in words is "two hundred twenty-one million, eight hundred fifty-six thousand, seven hundred twenty-nine".