19991278234 has 4 divisors (see below), whose sum is σ = 29986917354. Its totient is φ = 9995639116.

The previous prime is 19991278217. The next prime is 19991278249. The reversal of 19991278234 is 43287219991.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 19607000625 + 384277609 = 140025^2 + 19603^2 .

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 as a sum of consecutive naturals, namely, 4997819557 + ... + 4997819560.

Almost surely, 2^19991278234 is an apocalyptic number.

19991278234 is a deficient number, since it is larger than the sum of its proper divisors (9995639120).

19991278234 is an equidigital number, since it uses as much as digits as its factorization.

19991278234 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9995639119.

The product of its digits is 1959552, while the sum is 55.

The spelling of 19991278234 in words is "nineteen billion, nine hundred ninety-one million, two hundred seventy-eight thousand, two hundred thirty-four".