19717799949 has 20 divisors (see below), whose sum is σ = 29569627164. Its totient is φ = 13094037504.

The previous prime is 19717799947. The next prime is 19717799989. The reversal of 19717799949 is 94999771791.

It can be written as a sum of positive squares in 2 ways, for example, as 19384992900 + 332807049 = 139230^2 + 18243^2 .

It is not a de Polignac number, because 19717799949 - 2¹ = 19717799947 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19717799947) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 452782 + ... + 494415.

Almost surely, 2^19717799949 is an apocalyptic number.

It is an amenable number.

19717799949 is a deficient number, since it is larger than the sum of its proper divisors (9851827215).

19717799949 is an equidigital number, since it uses as much as digits as its factorization.

19717799949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 947466 (or 947457 counting only the distinct ones).

The product of its digits is 81015228, while the sum is 72.

The spelling of 19717799949 in words is "nineteen billion, seven hundred seventeen million, seven hundred ninety-nine thousand, nine hundred forty-nine".