18408729 has 4 divisors (see below), whose sum is σ = 24544976. Its totient is φ = 12272484.

The previous prime is 18408679. The next prime is 18408737. The reversal of 18408729 is 92780481.

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.

It is not a de Polignac number, because 18408729 - 2¹⁷ = 18277657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18408749) 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, 3068119 + ... + 3068124.

It is an arithmetic number, because the mean of its divisors is an integer number (6136244).

Almost surely, 2^18408729 is an apocalyptic number.

It is an amenable number.

18408729 is a deficient number, since it is larger than the sum of its proper divisors (6136247).

18408729 is an equidigital number, since it uses as much as digits as its factorization.

18408729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6136246.

The product of its (nonzero) digits is 32256, while the sum is 39.

The square root of 18408729 is about 4290.5394765694. The cubic root of 18408729 is about 264.0429653441.

The spelling of 18408729 in words is "eighteen million, four hundred eight thousand, seven hundred twenty-nine".