19987381 has 4 divisors (see below), whose sum is σ = 20067264. Its totient is φ = 19907500.

The previous prime is 19987379. The next prime is 19987399. The reversal of 19987381 is 18378991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 19987381 - 2¹ = 19987379 is a prime.

It is a super-2 number, since 2×19987381² = 798990798478322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19987301) 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, 39565 + ... + 40066.

It is an arithmetic number, because the mean of its divisors is an integer number (5016816).

Almost surely, 2^19987381 is an apocalyptic number.

It is an amenable number.

19987381 is a deficient number, since it is larger than the sum of its proper divisors (79883).

19987381 is an equidigital number, since it uses as much as digits as its factorization.

19987381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79882.

The product of its digits is 108864, while the sum is 46.

The square root of 19987381 is about 4470.7248852954. The cubic root of 19987381 is about 271.3846609221.

The spelling of 19987381 in words is "nineteen million, nine hundred eighty-seven thousand, three hundred eighty-one".