19949591693 has 4 divisors (see below), whose sum is σ = 20132615580. Its totient is φ = 19766567808.

The previous prime is 19949591689. The next prime is 19949591729. The reversal of 19949591693 is 39619594991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 39619594991 = 1223 ⋅32395417.

It can be written as a sum of positive squares in 2 ways, for example, as 5404749289 + 14544842404 = 73517^2 + 120602^2 .

It is a cyclic number.

It is not a de Polignac number, because 19949591693 - 2² = 19949591689 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 (19949591393) 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, 91511780 + ... + 91511997.

It is an arithmetic number, because the mean of its divisors is an integer number (5033153895).

Almost surely, 2^19949591693 is an apocalyptic number.

It is an amenable number.

19949591693 is a deficient number, since it is larger than the sum of its proper divisors (183023887).

19949591693 is a wasteful number, since it uses less digits than its factorization.

19949591693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183023886.

The product of its digits is 21257640, while the sum is 65.

The spelling of 19949591693 in words is "nineteen billion, nine hundred forty-nine million, five hundred ninety-one thousand, six hundred ninety-three".