19989579797 has 4 divisors (see below), whose sum is σ = 21806814336. Its totient is φ = 18172345260.

The previous prime is 19989579763. The next prime is 19989579803. The reversal of 19989579797 is 79797598991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 79797598991 = 11 ⋅7254327181.

It is a cyclic number.

It is not a de Polignac number, because 19989579797 - 2¹⁴ = 19989563413 is a prime.

It is a super-2 number, since 2×19989579797² (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 (19989579097) 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, 908617253 + ... + 908617274.

It is an arithmetic number, because the mean of its divisors is an integer number (5451703584).

Almost surely, 2^19989579797 is an apocalyptic number.

It is an amenable number.

19989579797 is a deficient number, since it is larger than the sum of its proper divisors (1817234539).

19989579797 is a wasteful number, since it uses less digits than its factorization.

19989579797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1817234538.

The product of its digits is 810152280, while the sum is 80.

The spelling of 19989579797 in words is "nineteen billion, nine hundred eighty-nine million, five hundred seventy-nine thousand, seven hundred ninety-seven".