19993639991 has 4 divisors (see below), whose sum is σ = 21531612312. Its totient is φ = 18455667672.

The previous prime is 19993639987. The next prime is 19993639993.

19993639991 is nontrivially palindromic in base 10.

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

It is not a de Polignac number, because 19993639991 - 2² = 19993639987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19993639993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 768986141 + ... + 768986166.

It is an arithmetic number, because the mean of its divisors is an integer number (5382903078).

Almost surely, 2^19993639991 is an apocalyptic number.

19993639991 is a deficient number, since it is larger than the sum of its proper divisors (1537972321).

19993639991 is a wasteful number, since it uses less digits than its factorization.

19993639991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1537972320.

The product of its digits is 28697814, while the sum is 68.

The spelling of 19993639991 in words is "nineteen billion, nine hundred ninety-three million, six hundred thirty-nine thousand, nine hundred ninety-one".