228393721 has 4 divisors (see below), whose sum is σ = 228640500. Its totient is φ = 228146944.

The previous prime is 228393707. The next prime is 228393731. The reversal of 228393721 is 127393822.

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 11155600 + 217238121 = 3340^2 + 14739^2 .

It is a cyclic number.

It is not a de Polignac number, because 228393721 - 2²³ = 220005113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (228393731) 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, 121996 + ... + 123853.

It is an arithmetic number, because the mean of its divisors is an integer number (57160125).

Almost surely, 2^228393721 is an apocalyptic number.

It is an amenable number.

228393721 is a deficient number, since it is larger than the sum of its proper divisors (246779).

228393721 is an equidigital number, since it uses as much as digits as its factorization.

228393721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246778.

The product of its digits is 36288, while the sum is 37.

The square root of 228393721 is about 15112.7006521005. The cubic root of 228393721 is about 611.2629223197.

The spelling of 228393721 in words is "two hundred twenty-eight million, three hundred ninety-three thousand, seven hundred twenty-one".