18531481 has 4 divisors (see below), whose sum is σ = 18541072. Its totient is φ = 18521892.

The previous prime is 18531439. The next prime is 18531511. The reversal of 18531481 is 18413581.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 18531481 - 2¹⁵ = 18498713 is a prime.

It is a super-2 number, since 2×18531481² = 686831576106722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18531421) 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, 771 + ... + 6136.

It is an arithmetic number, because the mean of its divisors is an integer number (4635268).

Almost surely, 2^18531481 is an apocalyptic number.

It is an amenable number.

18531481 is a deficient number, since it is larger than the sum of its proper divisors (9591).

18531481 is an equidigital number, since it uses as much as digits as its factorization.

18531481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9590.

The product of its digits is 3840, while the sum is 31.

The square root of 18531481 is about 4304.8206699002. The cubic root of 18531481 is about 264.6285575674.

The spelling of 18531481 in words is "eighteen million, five hundred thirty-one thousand, four hundred eighty-one".