1818661591 has 2 divisors, whose sum is σ = 1818661592. Its totient is φ = 1818661590.

The previous prime is 1818661583. The next prime is 1818661631. The reversal of 1818661591 is 1951668181.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1818661591 - 2³ = 1818661583 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1818661561) 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, 909330795 + 909330796.

It is an arithmetic number, because the mean of its divisors is an integer number (909330796).

Almost surely, 2^1818661591 is an apocalyptic number.

1818661591 is a deficient number, since it is larger than the sum of its proper divisors (1).

1818661591 is an equidigital number, since it uses as much as digits as its factorization.

1818661591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 103680, while the sum is 46.

The square root of 1818661591 is about 42645.7687350105. The cubic root of 1818661591 is about 1220.6297901692.

The spelling of 1818661591 in words is "one billion, eight hundred eighteen million, six hundred sixty-one thousand, five hundred ninety-one".