19999999709 has 4 divisors (see below), whose sum is σ = 20051413980. Its totient is φ = 19948585440.

The previous prime is 19999999693. The next prime is 19999999717. The reversal of 19999999709 is 90799999991.

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

It can be written as a sum of positive squares in 2 ways, for example, as 13176744100 + 6823255609 = 114790^2 + 82603^2 .

It is a cyclic number.

It is not a de Polignac number, because 19999999709 - 2⁴ = 19999999693 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 (19999999729) 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, 25706552 + ... + 25707329.

It is an arithmetic number, because the mean of its divisors is an integer number (5012853495).

Almost surely, 2^19999999709 is an apocalyptic number.

It is an amenable number.

19999999709 is a deficient number, since it is larger than the sum of its proper divisors (51414271).

19999999709 is an equidigital number, since it uses as much as digits as its factorization.

19999999709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51414270.

The product of its (nonzero) digits is 301327047, while the sum is 80.

The spelling of 19999999709 in words is "nineteen billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, seven hundred nine".