19987881 has 8 divisors (see below), whose sum is σ = 27370944. Its totient is φ = 12965040.

The previous prime is 19987879. The next prime is 19987907. The reversal of 19987881 is 18878991.

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

It is not a de Polignac number, because 19987881 - 2¹ = 19987879 is a prime.

It is a super-2 number, since 2×19987881² = 799030773740322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (19987841) 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, 89925 + ... + 90146.

It is an arithmetic number, because the mean of its divisors is an integer number (3421368).

Almost surely, 2^19987881 is an apocalyptic number.

It is an amenable number.

19987881 is a deficient number, since it is larger than the sum of its proper divisors (7383063).

19987881 is a wasteful number, since it uses less digits than its factorization.

19987881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180111.

The product of its digits is 290304, while the sum is 51.

The square root of 19987881 is about 4470.7808042891. The cubic root of 19987881 is about 271.3869238699.

The spelling of 19987881 in words is "nineteen million, nine hundred eighty-seven thousand, eight hundred eighty-one".