18722217 has 8 divisors (see below), whose sum is σ = 24986560. Its totient is φ = 12469680.

The previous prime is 18722191. The next prime is 18722267. The reversal of 18722217 is 71222781.

It is a happy number.

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

It is not a de Polignac number, because 18722217 - 2⁷ = 18722089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18722267) 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, 1884 + ... + 6402.

It is an arithmetic number, because the mean of its divisors is an integer number (3123320).

Almost surely, 2^18722217 is an apocalyptic number.

It is an amenable number.

18722217 is a deficient number, since it is larger than the sum of its proper divisors (6264343).

18722217 is a wasteful number, since it uses less digits than its factorization.

18722217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5903.

The product of its digits is 3136, while the sum is 30.

The square root of 18722217 is about 4326.9177251249. The cubic root of 18722217 is about 265.5333603514.

Adding to 18722217 its reverse (71222781), we get a palindrome (89944998).

The spelling of 18722217 in words is "eighteen million, seven hundred twenty-two thousand, two hundred seventeen".