18021309 has 8 divisors (see below), whose sum is σ = 25441920. Its totient is φ = 11307456.

The previous prime is 18021307. The next prime is 18021319. The reversal of 18021309 is 90312081.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18021309 - 2¹ = 18021307 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18021301) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 176629 + ... + 176730.

It is an arithmetic number, because the mean of its divisors is an integer number (3180240).

Almost surely, 2^18021309 is an apocalyptic number.

It is an amenable number.

18021309 is a deficient number, since it is larger than the sum of its proper divisors (7420611).

18021309 is a wasteful number, since it uses less digits than its factorization.

18021309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 353379.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 18021309 is about 4245.1512340552. The cubic root of 18021309 is about 262.1775160054.

The spelling of 18021309 in words is "eighteen million, twenty-one thousand, three hundred nine".