228213781 has 2 divisors, whose sum is σ = 228213782. Its totient is φ = 228213780.

The previous prime is 228213767. The next prime is 228213851. The reversal of 228213781 is 187312822.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 157502500 + 70711281 = 12550^2 + 8409^2 .

It is a cyclic number.

It is not a de Polignac number, because 228213781 - 2⁷ = 228213653 is a prime.

It is a super-2 number, since 2×228213781² = 104163059676631922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (228213721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 114106890 + 114106891.

It is an arithmetic number, because the mean of its divisors is an integer number (114106891).

Almost surely, 2^228213781 is an apocalyptic number.

It is an amenable number.

228213781 is a deficient number, since it is larger than the sum of its proper divisors (1).

228213781 is an equidigital number, since it uses as much as digits as its factorization.

228213781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10752, while the sum is 34.

The square root of 228213781 is about 15106.7462082343. The cubic root of 228213781 is about 611.1023523067.

The spelling of 228213781 in words is "two hundred twenty-eight million, two hundred thirteen thousand, seven hundred eighty-one".