18321857881 has 2 divisors, whose sum is σ = 18321857882. Its totient is φ = 18321857880.

The previous prime is 18321857849. The next prime is 18321857929. The reversal of 18321857881 is 18875812381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18209073481 + 112784400 = 134941^2 + 10620^2 .

It is a cyclic number.

It is not a de Polignac number, because 18321857881 - 2⁵ = 18321857849 is a prime.

It is a super-2 number, since 2×18321857881² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18321867881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9160928940 + 9160928941.

It is an arithmetic number, because the mean of its divisors is an integer number (9160928941).

Almost surely, 2^18321857881 is an apocalyptic number.

It is an amenable number.

18321857881 is a deficient number, since it is larger than the sum of its proper divisors (1).

18321857881 is an equidigital number, since it uses as much as digits as its factorization.

18321857881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 860160, while the sum is 52.

The spelling of 18321857881 in words is "eighteen billion, three hundred twenty-one million, eight hundred fifty-seven thousand, eight hundred eighty-one".