19998785537639 has 4 divisors (see below), whose sum is σ = 19998989047224. Its totient is φ = 19998582028056.

The previous prime is 19998785537623. The next prime is 19998785537651. The reversal of 19998785537639 is 93673558789991.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 19998785537639 - 2⁴ = 19998785537623 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 (19998785537669) 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, 101607317 + ... + 101803950.

It is an arithmetic number, because the mean of its divisors is an integer number (4999747261806).

Almost surely, 2^{19998785537639} is an apocalyptic number.

19998785537639 is a deficient number, since it is larger than the sum of its proper divisors (203509585).

19998785537639 is an equidigital number, since it uses as much as digits as its factorization.

19998785537639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203509584.

The product of its digits is 27776649600, while the sum is 89.

The spelling of 19998785537639 in words is "nineteen trillion, nine hundred ninety-eight billion, seven hundred eighty-five million, five hundred thirty-seven thousand, six hundred thirty-nine".