18728531 has 8 divisors (see below), whose sum is σ = 19101744. Its totient is φ = 18359200.

The previous prime is 18728503. The next prime is 18728533. The reversal of 18728531 is 13582781.

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

It is a cyclic number.

It is not a de Polignac number, because 18728531 - 2⁶ = 18728467 is a prime.

It is a super-2 number, since 2×18728531² = 701515746835922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18728491 and 18728500.

It is not an unprimeable number, because it can be changed into a prime (18728533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9941 + ... + 11673.

It is an arithmetic number, because the mean of its divisors is an integer number (2387718).

Almost surely, 2^18728531 is an apocalyptic number.

18728531 is a deficient number, since it is larger than the sum of its proper divisors (373213).

18728531 is a wasteful number, since it uses less digits than its factorization.

18728531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1941.

The product of its digits is 13440, while the sum is 35.

The square root of 18728531 is about 4327.6472823002. The cubic root of 18728531 is about 265.5632070517.

The spelling of 18728531 in words is "eighteen million, seven hundred twenty-eight thousand, five hundred thirty-one".