19806391838 has 16 divisors (see below), whose sum is σ = 29773027440. Its totient is φ = 9882067200.

The previous prime is 19806391823. The next prime is 19806391867. The reversal of 19806391838 is 83819360891.

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 7 ways as a sum of consecutive naturals, for example, 3762128 + ... + 3767388.

It is an arithmetic number, because the mean of its divisors is an integer number (1860814215).

Almost surely, 2^19806391838 is an apocalyptic number.

19806391838 is a deficient number, since it is larger than the sum of its proper divisors (9966635602).

19806391838 is a wasteful number, since it uses less digits than its factorization.

19806391838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8923.

The product of its (nonzero) digits is 2239488, while the sum is 56.

The spelling of 19806391838 in words is "nineteen billion, eight hundred six million, three hundred ninety-one thousand, eight hundred thirty-eight".