19806704639 has 4 divisors (see below), whose sum is σ = 19807049256. Its totient is φ = 19806360024.

The previous prime is 19806704597. The next prime is 19806704647. The reversal of 19806704639 is 93640760891.

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

It is a cyclic number.

It is not a de Polignac number, because 19806704639 - 2¹⁶ = 19806639103 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 (19806704669) 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, 62969 + ... + 208754.

It is an arithmetic number, because the mean of its divisors is an integer number (4951762314).

Almost surely, 2^19806704639 is an apocalyptic number.

19806704639 is a deficient number, since it is larger than the sum of its proper divisors (344617).

19806704639 is an equidigital number, since it uses as much as digits as its factorization.

19806704639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344616.

The product of its (nonzero) digits is 1959552, while the sum is 53.

The spelling of 19806704639 in words is "nineteen billion, eight hundred six million, seven hundred four thousand, six hundred thirty-nine".