18681337 has 4 divisors (see below), whose sum is σ = 19186276. Its totient is φ = 18176400.

The previous prime is 18681331. The next prime is 18681343. The reversal of 18681337 is 73318681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 73318681 = 6449 ⋅11369.

It is an interprime number because it is at equal distance from previous prime (18681331) and next prime (18681343).

It can be written as a sum of positive squares in 2 ways, for example, as 14584761 + 4096576 = 3819^2 + 2024^2 .

It is a cyclic number.

It is not a de Polignac number, because 18681337 - 2³ = 18681329 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 504901 = 18681337 / (1 + 8 + 6 + 8 + 1 + 3 + 3 + 7).

It is a junction number, because it is equal to n+sod(n) for n = 18681296 and 18681305.

It is not an unprimeable number, because it can be changed into a prime (18681331) 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, 252414 + ... + 252487.

It is an arithmetic number, because the mean of its divisors is an integer number (4796569).

Almost surely, 2^18681337 is an apocalyptic number.

It is an amenable number.

18681337 is a deficient number, since it is larger than the sum of its proper divisors (504939).

18681337 is an equidigital number, since it uses as much as digits as its factorization.

18681337 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 504938.

The product of its digits is 24192, while the sum is 37.

The square root of 18681337 is about 4322.1912266812. The cubic root of 18681337 is about 265.3399553002.

The spelling of 18681337 in words is "eighteen million, six hundred eighty-one thousand, three hundred thirty-seven".