19991985797 has 16 divisors (see below), whose sum is σ = 23045468160. Its totient is φ = 16988082048.

The previous prime is 19991985791. The next prime is 19991985799. The reversal of 19991985797 is 79758919991.

It is not a de Polignac number, because 19991985797 - 2⁴ = 19991985781 is a prime.

It is a super-2 number, since 2×19991985797² (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 (19991985791) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1262513 + ... + 1278249.

It is an arithmetic number, because the mean of its divisors is an integer number (1440341760).

Almost surely, 2^19991985797 is an apocalyptic number.

It is an amenable number.

19991985797 is a deficient number, since it is larger than the sum of its proper divisors (3053482363).

19991985797 is a wasteful number, since it uses less digits than its factorization.

19991985797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17300.

The product of its digits is 115736040, while the sum is 74.

The spelling of 19991985797 in words is "nineteen billion, nine hundred ninety-one million, nine hundred eighty-five thousand, seven hundred ninety-seven".