18491044657 has 2 divisors, whose sum is σ = 18491044658. Its totient is φ = 18491044656.

The previous prime is 18491044651. The next prime is 18491044669. The reversal of 18491044657 is 75644019481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13877782416 + 4613262241 = 117804^2 + 67921^2 .

It is a cyclic number.

It is not a de Polignac number, because 18491044657 - 2³¹ = 16343561009 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18491044657.

It is not a weakly prime, because it can be changed into another prime (18491044651) 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, 9245522328 + 9245522329.

It is an arithmetic number, because the mean of its divisors is an integer number (9245522329).

Almost surely, 2^18491044657 is an apocalyptic number.

It is an amenable number.

18491044657 is a deficient number, since it is larger than the sum of its proper divisors (1).

18491044657 is an equidigital number, since it uses as much as digits as its factorization.

18491044657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 967680, while the sum is 49.

The spelling of 18491044657 in words is "eighteen billion, four hundred ninety-one million, forty-four thousand, six hundred fifty-seven".