228521 has 2 divisors, whose sum is σ = 228522. Its totient is φ = 228520.

The previous prime is 228517. The next prime is 228523. The reversal of 228521 is 125822.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 215296 + 13225 = 464^2 + 115^2 .

It is a cyclic number.

It is not a de Polignac number, because 228521 - 2² = 228517 is a prime.

It is a Sophie Germain prime.

Together with 228523, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 228493 and 228502.

It is not a weakly prime, because it can be changed into another prime (228523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 114260 + 114261.

It is an arithmetic number, because the mean of its divisors is an integer number (114261).

2²²⁸⁵²¹ is an apocalyptic number.

It is an amenable number.

228521 is a deficient number, since it is larger than the sum of its proper divisors (1).

228521 is an equidigital number, since it uses as much as digits as its factorization.

228521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 320, while the sum is 20.

The square root of 228521 is about 478.0387013621. The cubic root of 228521 is about 61.1376449208.

The spelling of 228521 in words is "two hundred twenty-eight thousand, five hundred twenty-one".