228523781 has 4 divisors (see below), whose sum is σ = 228770700. Its totient is φ = 228276864.

The previous prime is 228523759. The next prime is 228523807. The reversal of 228523781 is 187325822.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 32103556 + 196420225 = 5666^2 + 14015^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-228523781 is a prime.

It is a super-2 number, since 2×228523781² = 104446236965071922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (228523721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122066 + ... + 123923.

It is an arithmetic number, because the mean of its divisors is an integer number (57192675).

Almost surely, 2^228523781 is an apocalyptic number.

It is an amenable number.

228523781 is a deficient number, since it is larger than the sum of its proper divisors (246919).

228523781 is an equidigital number, since it uses as much as digits as its factorization.

228523781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246918.

The product of its digits is 53760, while the sum is 38.

The square root of 228523781 is about 15117.0030429315. The cubic root of 228523781 is about 611.3789292592.

The spelling of 228523781 in words is "two hundred twenty-eight million, five hundred twenty-three thousand, seven hundred eighty-one".