19979218547 has 4 divisors (see below), whose sum is σ = 20162514240. Its totient is φ = 19795922856.

The previous prime is 19979218543. The next prime is 19979218577. The reversal of 19979218547 is 74581297991.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 19979218547 - 2² = 19979218543 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19979218547.

It is not an unprimeable number, because it can be changed into a prime (19979218543) 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, 91647683 + ... + 91647900.

It is an arithmetic number, because the mean of its divisors is an integer number (5040628560).

Almost surely, 2^19979218547 is an apocalyptic number.

19979218547 is a deficient number, since it is larger than the sum of its proper divisors (183295693).

19979218547 is a wasteful number, since it uses less digits than its factorization.

19979218547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183295692.

The product of its digits is 11430720, while the sum is 62.

The spelling of 19979218547 in words is "nineteen billion, nine hundred seventy-nine million, two hundred eighteen thousand, five hundred forty-seven".