19873447985 has 4 divisors (see below), whose sum is σ = 23848137588. Its totient is φ = 15898758384.

The previous prime is 19873447943. The next prime is 19873448003. The reversal of 19873447985 is 58974437891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 58974437891 = 1399 ⋅42154709.

It can be written as a sum of positive squares in 2 ways, for example, as 2630869264 + 17242578721 = 51292^2 + 131311^2 .

It is a cyclic number.

It is not a de Polignac number, because 19873447985 - 2³⁴ = 2693578801 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1987344794 + ... + 1987344803.

It is an arithmetic number, because the mean of its divisors is an integer number (5962034397).

Almost surely, 2^19873447985 is an apocalyptic number.

It is an amenable number.

19873447985 is a deficient number, since it is larger than the sum of its proper divisors (3974689603).

19873447985 is an equidigital number, since it uses as much as digits as its factorization.

19873447985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3974689602.

The product of its digits is 60963840, while the sum is 65.

The spelling of 19873447985 in words is "nineteen billion, eight hundred seventy-three million, four hundred forty-seven thousand, nine hundred eighty-five".