18808921858 has 4 divisors (see below), whose sum is σ = 28213382790. Its totient is φ = 9404460928.

The previous prime is 18808921823. The next prime is 18808921939. The reversal of 18808921858 is 85812980881.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 85812980881 = 857 ⋅100131833.

It can be written as a sum of positive squares in only one way, i.e., 18091057009 + 717864849 = 134503^2 + 26793^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4702230463 + ... + 4702230466.

Almost surely, 2^18808921858 is an apocalyptic number.

18808921858 is a deficient number, since it is larger than the sum of its proper divisors (9404460932).

18808921858 is an equidigital number, since it uses as much as digits as its factorization.

18808921858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9404460931.

The product of its (nonzero) digits is 2949120, while the sum is 58.

The spelling of 18808921858 in words is "eighteen billion, eight hundred eight million, nine hundred twenty-one thousand, eight hundred fifty-eight".