18319521 has 24 divisors (see below), whose sum is σ = 27153280. Its totient is φ = 10977120.

The previous prime is 18319513. The next prime is 18319529. The reversal of 18319521 is 12591381.

It is an interprime number because it is at equal distance from previous prime (18319513) and next prime (18319529).

It is not a de Polignac number, because 18319521 - 2³ = 18319513 is a prime.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (18319529) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 39336 + ... + 39798.

Almost surely, 2^18319521 is an apocalyptic number.

18319521 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18319521 is a deficient number, since it is larger than the sum of its proper divisors (8833759).

18319521 is a wasteful number, since it uses less digits than its factorization.

18319521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 597 (or 586 counting only the distinct ones).

The product of its digits is 2160, while the sum is 30.

The square root of 18319521 is about 4280.1309559405. The cubic root of 18319521 is about 263.6157604733.

The spelling of 18319521 in words is "eighteen million, three hundred nineteen thousand, five hundred twenty-one".