19899984278 has 4 divisors (see below), whose sum is σ = 29849976420. Its totient is φ = 9949992138.

The previous prime is 19899984277. The next prime is 19899984289. The reversal of 19899984278 is 87248999891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87248999891 = 233 ⋅374459227.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19899984277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4974996068 + ... + 4974996071.

It is an arithmetic number, because the mean of its divisors is an integer number (7462494105).

Almost surely, 2^19899984278 is an apocalyptic number.

19899984278 is a deficient number, since it is larger than the sum of its proper divisors (9949992142).

19899984278 is an equidigital number, since it uses as much as digits as its factorization.

19899984278 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9949992141.

The product of its digits is 188116992, while the sum is 74.

The spelling of 19899984278 in words is "nineteen billion, eight hundred ninety-nine million, nine hundred eighty-four thousand, two hundred seventy-eight".