19815550555 has 4 divisors (see below), whose sum is σ = 23778660672. Its totient is φ = 15852440440.

The previous prime is 19815550553. The next prime is 19815550561. The reversal of 19815550555 is 55505551891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 55505551891 = 67 ⋅828441073.

It is not a de Polignac number, because 19815550555 - 2¹ = 19815550553 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19815550499 and 19815550508.

It is not an unprimeable number, because it can be changed into a prime (19815550553) 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, 1981555051 + ... + 1981555060.

It is an arithmetic number, because the mean of its divisors is an integer number (5944665168).

Almost surely, 2^19815550555 is an apocalyptic number.

19815550555 is a deficient number, since it is larger than the sum of its proper divisors (3963110117).

19815550555 is an equidigital number, since it uses as much as digits as its factorization.

19815550555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3963110116.

The product of its (nonzero) digits is 1125000, while the sum is 49.

The spelling of 19815550555 in words is "nineteen billion, eight hundred fifteen million, five hundred fifty thousand, five hundred fifty-five".