18213817 has 4 divisors (see below), whose sum is σ = 19285236. Its totient is φ = 17142400.

The previous prime is 18213803. The next prime is 18213823. The reversal of 18213817 is 71831281.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5851561 + 12362256 = 2419^2 + 3516^2 .

It is a cyclic number.

It is not a de Polignac number, because 18213817 - 2¹¹ = 18211769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18213857) 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, 535684 + ... + 535717.

It is an arithmetic number, because the mean of its divisors is an integer number (4821309).

Almost surely, 2^18213817 is an apocalyptic number.

18213817 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

18213817 is a deficient number, since it is larger than the sum of its proper divisors (1071419).

18213817 is a wasteful number, since it uses less digits than its factorization.

18213817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1071418.

The product of its digits is 2688, while the sum is 31.

The square root of 18213817 is about 4267.7648716863. The cubic root of 18213817 is about 263.1077594337.

The spelling of 18213817 in words is "eighteen million, two hundred thirteen thousand, eight hundred seventeen".