18509813 has 8 divisors (see below), whose sum is σ = 21181440. Its totient is φ = 15845040.

The previous prime is 18509809. The next prime is 18509839. The reversal of 18509813 is 31890581.

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

It is a cyclic number.

It is not a de Polignac number, because 18509813 - 2² = 18509809 is a prime.

It is a super-2 number, since 2×18509813² = 685226354589938, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18509873) 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, 7148 + ... + 9386.

It is an arithmetic number, because the mean of its divisors is an integer number (2647680).

Almost surely, 2^18509813 is an apocalyptic number.

It is an amenable number.

18509813 is a deficient number, since it is larger than the sum of its proper divisors (2671627).

18509813 is a wasteful number, since it uses less digits than its factorization.

18509813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3427.

The product of its (nonzero) digits is 8640, while the sum is 35.

The square root of 18509813 is about 4302.3032203693. The cubic root of 18509813 is about 264.5253780489.

The spelling of 18509813 in words is "eighteen million, five hundred nine thousand, eight hundred thirteen".