1818243781 has 2 divisors, whose sum is σ = 1818243782. Its totient is φ = 1818243780.

The previous prime is 1818243761. The next prime is 1818243787. The reversal of 1818243781 is 1873428181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1586747556 + 231496225 = 39834^2 + 15215^2 .

It is a cyclic number.

It is not a de Polignac number, because 1818243781 - 2²⁵ = 1784689349 is a prime.

It is a super-3 number, since 3×1818243781³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1818243787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 909121890 + 909121891.

It is an arithmetic number, because the mean of its divisors is an integer number (909121891).

Almost surely, 2^1818243781 is an apocalyptic number.

It is an amenable number.

1818243781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1818243781 is an equidigital number, since it uses as much as digits as its factorization.

1818243781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 86016, while the sum is 43.

The square root of 1818243781 is about 42640.8698433791. The cubic root of 1818243781 is about 1220.5363092647.

The spelling of 1818243781 in words is "one billion, eight hundred eighteen million, two hundred forty-three thousand, seven hundred eighty-one".