18851553409 has 4 divisors (see below), whose sum is σ = 20301672916. Its totient is φ = 17401433904.

The previous prime is 18851553401. The next prime is 18851553421. The reversal of 18851553409 is 90435515881.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90435515881 = 91621 ⋅987061.

It can be written as a sum of positive squares in 2 ways, for example, as 10926102784 + 7925450625 = 104528^2 + 89025^2 .

It is a cyclic number.

It is not a de Polignac number, because 18851553409 - 2³ = 18851553401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18851553401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 725059734 + ... + 725059759.

It is an arithmetic number, because the mean of its divisors is an integer number (5075418229).

Almost surely, 2^18851553409 is an apocalyptic number.

It is an amenable number.

18851553409 is a deficient number, since it is larger than the sum of its proper divisors (1450119507).

18851553409 is a wasteful number, since it uses less digits than its factorization.

18851553409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1450119506.

The product of its (nonzero) digits is 864000, while the sum is 49.

The spelling of 18851553409 in words is "eighteen billion, eight hundred fifty-one million, five hundred fifty-three thousand, four hundred nine".