228523721 has 2 divisors, whose sum is σ = 228523722. Its totient is φ = 228523720.

The previous prime is 228523663. The next prime is 228523727. The reversal of 228523721 is 127325822.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 226833721 + 1690000 = 15061^2 + 1300^2 .

It is a cyclic number.

It is not a de Polignac number, because 228523721 - 2⁶ = 228523657 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (228523727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 114261860 + 114261861.

It is an arithmetic number, because the mean of its divisors is an integer number (114261861).

Almost surely, 2^228523721 is an apocalyptic number.

It is an amenable number.

228523721 is a deficient number, since it is larger than the sum of its proper divisors (1).

228523721 is an equidigital number, since it uses as much as digits as its factorization.

228523721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13440, while the sum is 32.

The square root of 228523721 is about 15117.0010584110. The cubic root of 228523721 is about 611.3788757524.

Subtracting from 228523721 its sum of digits (32), we obtain a square (228523689 = 15117²).

The spelling of 228523721 in words is "two hundred twenty-eight million, five hundred twenty-three thousand, seven hundred twenty-one".