19991278278 has 32 divisors (see below), whose sum is σ = 44431795200. Its totient is φ = 6662749608.

The previous prime is 19991278261. The next prime is 19991278283. The reversal of 19991278278 is 87287219991.

19991278278 is a `hidden beast` number, since 1 + 9 + 9 + 91 + 278 + 278 = 666.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 388275 + ... + 436737.

It is an arithmetic number, because the mean of its divisors is an integer number (1388493600).

Almost surely, 2^19991278278 is an apocalyptic number.

19991278278 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

19991278278 is an abundant number, since it is smaller than the sum of its proper divisors (24440516922).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19991278278 is a wasteful number, since it uses less digits than its factorization.

19991278278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56113 (or 56107 counting only the distinct ones).

The product of its digits is 9144576, while the sum is 63.

The spelling of 19991278278 in words is "nineteen billion, nine hundred ninety-one million, two hundred seventy-eight thousand, two hundred seventy-eight".