18712217 has 4 divisors (see below), whose sum is σ = 18735360. Its totient is φ = 18689076.

The previous prime is 18712201. The next prime is 18712247. The reversal of 18712217 is 71221781.

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 a cyclic number.

It is not a de Polignac number, because 18712217 - 2⁴ = 18712201 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18712217.

It is not an unprimeable number, because it can be changed into a prime (18712247) 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, 10313 + ... + 11990.

It is an arithmetic number, because the mean of its divisors is an integer number (4683840).

Almost surely, 2^18712217 is an apocalyptic number.

It is an amenable number.

18712217 is a deficient number, since it is larger than the sum of its proper divisors (23143).

18712217 is an equidigital number, since it uses as much as digits as its factorization.

18712217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23142.

The product of its digits is 1568, while the sum is 29.

The square root of 18712217 is about 4325.7620137960. The cubic root of 18712217 is about 265.4860759494.

Adding to 18712217 its reverse (71221781), we get a palindrome (89933998).

The spelling of 18712217 in words is "eighteen million, seven hundred twelve thousand, two hundred seventeen".