19998887 has 4 divisors (see below), whose sum is σ = 21051480. Its totient is φ = 18946296.

The previous prime is 19998877. The next prime is 19998899. The reversal of 19998887 is 78889991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78889991 = 227 ⋅347533.

It is a cyclic number.

It is not a de Polignac number, because 19998887 - 2²² = 15804583 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 (19998877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 526268 + ... + 526305.

It is an arithmetic number, because the mean of its divisors is an integer number (5262870).

Almost surely, 2^19998887 is an apocalyptic number.

19998887 is a deficient number, since it is larger than the sum of its proper divisors (1052593).

19998887 is a wasteful number, since it uses less digits than its factorization.

19998887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1052592.

The product of its digits is 2612736, while the sum is 59.

The square root of 19998887 is about 4472.0115160854. The cubic root of 19998887 is about 271.4367263214.

The spelling of 19998887 in words is "nineteen million, nine hundred ninety-eight thousand, eight hundred eighty-seven".