228131021 has 2 divisors, whose sum is σ = 228131022. Its totient is φ = 228131020.

The previous prime is 228131017. The next prime is 228131107. The reversal of 228131021 is 120131822.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 207072100 + 21058921 = 14390^2 + 4589^2 .

It is a cyclic number.

It is not a de Polignac number, because 228131021 - 2² = 228131017 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 228130984 and 228131002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (228131621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 114065510 + 114065511.

It is an arithmetic number, because the mean of its divisors is an integer number (114065511).

Almost surely, 2^228131021 is an apocalyptic number.

It is an amenable number.

228131021 is a deficient number, since it is larger than the sum of its proper divisors (1).

228131021 is an equidigital number, since it uses as much as digits as its factorization.

228131021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 228131021 is about 15104.0067862803. The cubic root of 228131021 is about 611.0284728281.

Adding to 228131021 its reverse (120131822), we get a palindrome (348262843).

The spelling of 228131021 in words is "two hundred twenty-eight million, one hundred thirty-one thousand, twenty-one".