18091857661 has 12 divisors (see below), whose sum is σ = 19373967900. Its totient is φ = 16883155520.

The previous prime is 18091857653. The next prime is 18091857671. The reversal of 18091857661 is 16675819081.

It can be written as a sum of positive squares in 2 ways, for example, as 7427164761 + 10664692900 = 86181^2 + 103270^2 .

It is not a de Polignac number, because 18091857661 - 2³ = 18091857653 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18091857599 and 18091857608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18091857631) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 395386 + ... + 438763.

It is an arithmetic number, because the mean of its divisors is an integer number (1614497325).

Almost surely, 2^18091857661 is an apocalyptic number.

It is an amenable number.

18091857661 is a deficient number, since it is larger than the sum of its proper divisors (1282110239).

18091857661 is an equidigital number, since it uses as much as digits as its factorization.

18091857661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 834236 (or 834213 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 52.

The spelling of 18091857661 in words is "eighteen billion, ninety-one million, eight hundred fifty-seven thousand, six hundred sixty-one".