228315721 has 2 divisors, whose sum is σ = 228315722. Its totient is φ = 228315720.

The previous prime is 228315697. The next prime is 228315739. The reversal of 228315721 is 127513822.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 223203600 + 5112121 = 14940^2 + 2261^2 .

It is a cyclic number.

It is not a de Polignac number, because 228315721 - 2²¹ = 226218569 is a prime.

It is not a weakly prime, because it can be changed into another prime (228315751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 114157860 + 114157861.

It is an arithmetic number, because the mean of its divisors is an integer number (114157861).

Almost surely, 2^228315721 is an apocalyptic number.

It is an amenable number.

228315721 is a deficient number, since it is larger than the sum of its proper divisors (1).

228315721 is an equidigital number, since it uses as much as digits as its factorization.

228315721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6720, while the sum is 31.

The square root of 228315721 is about 15110.1198208353. The cubic root of 228315721 is about 611.1933291388.

The spelling of 228315721 in words is "two hundred twenty-eight million, three hundred fifteen thousand, seven hundred twenty-one".