228189721 has 4 divisors (see below), whose sum is σ = 228225844. Its totient is φ = 228153600.

The previous prime is 228189673. The next prime is 228189727. The reversal of 228189721 is 127981822.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 68293696 + 159896025 = 8264^2 + 12645^2 .

It is a cyclic number.

It is not a de Polignac number, because 228189721 - 2¹³ = 228181529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (228189727) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5820 + ... + 22141.

It is an arithmetic number, because the mean of its divisors is an integer number (57056461).

Almost surely, 2^228189721 is an apocalyptic number.

It is an amenable number.

228189721 is a deficient number, since it is larger than the sum of its proper divisors (36123).

228189721 is an equidigital number, since it uses as much as digits as its factorization.

228189721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36122.

The product of its digits is 32256, while the sum is 40.

The square root of 228189721 is about 15105.9498542793. The cubic root of 228189721 is about 611.0808758950.

The spelling of 228189721 in words is "two hundred twenty-eight million, one hundred eighty-nine thousand, seven hundred twenty-one".