19817144917 has 4 divisors (see below), whose sum is σ = 19834887436. Its totient is φ = 19799402400.

The previous prime is 19817144891. The next prime is 19817144923. The reversal of 19817144917 is 71944171891.

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 3266579716 + 16550565201 = 57154^2 + 128649^2 .

It is a cyclic number.

It is not a de Polignac number, because 19817144917 - 2¹¹ = 19817142869 is a prime.

It is a super-2 number, since 2×19817144917² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19817144927) 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, 8869584 + ... + 8871817.

It is an arithmetic number, because the mean of its divisors is an integer number (4958721859).

Almost surely, 2^19817144917 is an apocalyptic number.

It is an amenable number.

19817144917 is a deficient number, since it is larger than the sum of its proper divisors (17742519).

19817144917 is a wasteful number, since it uses less digits than its factorization.

19817144917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17742518.

The product of its digits is 508032, while the sum is 52.

The spelling of 19817144917 in words is "nineteen billion, eight hundred seventeen million, one hundred forty-four thousand, nine hundred seventeen".