228720281 has 4 divisors (see below), whose sum is σ = 233035812. Its totient is φ = 224404752.

The previous prime is 228720241. The next prime is 228720307. The reversal of 228720281 is 182027822.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 182027822 = 2 ⋅91013911.

It can be written as a sum of positive squares in 2 ways, for example, as 74563225 + 154157056 = 8635^2 + 12416^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-228720281 is a prime.

It is a super-2 number, since 2×228720281² = 104625933881437922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (228720241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2157686 + ... + 2157791.

It is an arithmetic number, because the mean of its divisors is an integer number (58258953).

Almost surely, 2^228720281 is an apocalyptic number.

It is an amenable number.

228720281 is a deficient number, since it is larger than the sum of its proper divisors (4315531).

228720281 is an equidigital number, since it uses as much as digits as its factorization.

228720281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4315530.

The product of its (nonzero) digits is 7168, while the sum is 32.

The square root of 228720281 is about 15123.5009505075. The cubic root of 228720281 is about 611.5541138605.

The spelling of 228720281 in words is "two hundred twenty-eight million, seven hundred twenty thousand, two hundred eighty-one".