2243781 has 10 divisors (see below), whose sum is σ = 3351942. Its totient is φ = 1495800.

The previous prime is 2243777. The next prime is 2243789. The reversal of 2243781 is 1873422.

It can be written as a sum of positive squares in only one way, i.e., 1846881 + 396900 = 1359^2 + 630^2 .

It is not a de Polignac number, because 2243781 - 2² = 2243777 is a prime.

It is a super-2 number, since 2×2243781² = 10069106351922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

2243781 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2243789) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 13770 + ... + 13931.

2^2243781 is an apocalyptic number.

It is an amenable number.

2243781 is a deficient number, since it is larger than the sum of its proper divisors (1108161).

2243781 is an equidigital number, since it uses as much as digits as its factorization.

2243781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27713 (or 27704 counting only the distinct ones).

The product of its digits is 2688, while the sum is 27.

The square root of 2243781 is about 1497.9255655739. The cubic root of 2243781 is about 130.9162294876.

It can be divided in two parts, 224 and 3781, that added together give a triangular number (4005 = T₈₉).

The spelling of 2243781 in words is "two million, two hundred forty-three thousand, seven hundred eighty-one".