19985779 has 8 divisors (see below), whose sum is σ = 22019760. Its totient is φ = 17988000.

The previous prime is 19985773. The next prime is 19985803. The reversal of 19985779 is 97758991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19985779 - 2⁵ = 19985747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19985773) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7884 + ... + 10105.

It is an arithmetic number, because the mean of its divisors is an integer number (2752470).

Almost surely, 2^19985779 is an apocalyptic number.

19985779 is a deficient number, since it is larger than the sum of its proper divisors (2033981).

19985779 is a wasteful number, since it uses less digits than its factorization.

19985779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18101.

The product of its digits is 1428840, while the sum is 55.

The square root of 19985779 is about 4470.5457161291. The cubic root of 19985779 is about 271.3774101832.

It can be divided in two parts, 1998 and 5779, that added together give a palindrome (7777).

The spelling of 19985779 in words is "nineteen million, nine hundred eighty-five thousand, seven hundred seventy-nine".