1818733921 has 2 divisors, whose sum is σ = 1818733922. Its totient is φ = 1818733920.

The previous prime is 1818733907. The next prime is 1818733937. The reversal of 1818733921 is 1293378181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1618935696 + 199798225 = 40236^2 + 14135^2 .

It is a cyclic number.

It is not a de Polignac number, because 1818733921 - 2¹³ = 1818725729 is a prime.

It is not a weakly prime, because it can be changed into another prime (1818733991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 909366960 + 909366961.

It is an arithmetic number, because the mean of its divisors is an integer number (909366961).

Almost surely, 2^1818733921 is an apocalyptic number.

It is an amenable number.

1818733921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1818733921 is an equidigital number, since it uses as much as digits as its factorization.

1818733921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 43.

The square root of 1818733921 is about 42646.6167591287. The cubic root of 1818733921 is about 1220.6459718461.

The spelling of 1818733921 in words is "one billion, eight hundred eighteen million, seven hundred thirty-three thousand, nine hundred twenty-one".