18729919 has 4 divisors (see below), whose sum is σ = 20170696. Its totient is φ = 17289144.

The previous prime is 18729913. The next prime is 18729929. The reversal of 18729919 is 91992781.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 91992781 = 43 ⋅2139367.

It is a cyclic number.

It is not a de Polignac number, because 18729919 - 2⁷ = 18729791 is a prime.

It is a super-2 number, since 2×18729919² = 701619731493122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18729913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 720369 + ... + 720394.

It is an arithmetic number, because the mean of its divisors is an integer number (5042674).

Almost surely, 2^18729919 is an apocalyptic number.

18729919 is a deficient number, since it is larger than the sum of its proper divisors (1440777).

18729919 is a wasteful number, since it uses less digits than its factorization.

18729919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1440776.

The product of its digits is 81648, while the sum is 46.

The square root of 18729919 is about 4327.8076435997. The cubic root of 18729919 is about 265.5697673211.

The spelling of 18729919 in words is "eighteen million, seven hundred twenty-nine thousand, nine hundred nineteen".