18009729 has 16 divisors (see below), whose sum is σ = 27543040. Its totient is φ = 11618640.

The previous prime is 18009683. The next prime is 18009763. The reversal of 18009729 is 92790081.

It is a happy number.

It is not a de Polignac number, because 18009729 - 2¹² = 18005633 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18009693 and 18009702.

It is not an unprimeable number, because it can be changed into a prime (18009829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9922 + ... + 11595.

It is an arithmetic number, because the mean of its divisors is an integer number (1721440).

Almost surely, 2^18009729 is an apocalyptic number.

It is an amenable number.

18009729 is a deficient number, since it is larger than the sum of its proper divisors (9533311).

18009729 is a wasteful number, since it uses less digits than its factorization.

18009729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21557 (or 21551 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 18009729 is about 4243.7871058761. The cubic root of 18009729 is about 262.1213479406.

The spelling of 18009729 in words is "eighteen million, nine thousand, seven hundred twenty-nine".