19999887 has 16 divisors (see below), whose sum is σ = 27269088. Its totient is φ = 13034880.

The previous prime is 19999873. The next prime is 19999891. The reversal of 19999887 is 78899991.

19999887 = 19² + 20² + ... + 391².

It is not a de Polignac number, because 19999887 - 2⁸ = 19999631 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19999887.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19999817) 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, 53433 + ... + 53805.

It is an arithmetic number, because the mean of its divisors is an integer number (1704318).

Almost surely, 2^19999887 is an apocalyptic number.

19999887 is a deficient number, since it is larger than the sum of its proper divisors (7269201).

19999887 is a wasteful number, since it uses less digits than its factorization.

19999887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 730.

The product of its digits is 2939328, while the sum is 60.

The square root of 19999887 is about 4472.1233211977. The cubic root of 19999887 is about 271.4412504432.

The spelling of 19999887 in words is "nineteen million, nine hundred ninety-nine thousand, eight hundred eighty-seven".