1818055621 has 2 divisors, whose sum is σ = 1818055622. Its totient is φ = 1818055620.

The previous prime is 1818055619. The next prime is 1818055627. The reversal of 1818055621 is 1265508181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1529904996 + 288150625 = 39114^2 + 16975^2 .

It is a cyclic number.

It is not a de Polignac number, because 1818055621 - 2¹ = 1818055619 is a prime.

Together with 1818055619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1818055627) 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, 909027810 + 909027811.

It is an arithmetic number, because the mean of its divisors is an integer number (909027811).

Almost surely, 2^1818055621 is an apocalyptic number.

It is an amenable number.

1818055621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1818055621 is an equidigital number, since it uses as much as digits as its factorization.

1818055621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19200, while the sum is 37.

The square root of 1818055621 is about 42638.6634523175. The cubic root of 1818055621 is about 1220.4942056266.

The spelling of 1818055621 in words is "one billion, eight hundred eighteen million, fifty-five thousand, six hundred twenty-one".