218522309 has 12 divisors (see below), whose sum is σ = 225299232. Its totient is φ = 211900920.

The previous prime is 218522299. The next prime is 218522321. The reversal of 218522309 is 903225812.

It is a happy number.

It is not a de Polignac number, because 218522309 - 2¹⁶ = 218456773 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218522389) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 337424 + ... + 338070.

It is an arithmetic number, because the mean of its divisors is an integer number (18774936).

Almost surely, 2^218522309 is an apocalyptic number.

It is an amenable number.

218522309 is a deficient number, since it is larger than the sum of its proper divisors (6776923).

218522309 is an frugal number, since it uses more digits than its factorization.

218522309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 856 (or 785 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 218522309 is about 14782.5000930154. The cubic root of 218522309 is about 602.3264391060.

The spelling of 218522309 in words is "two hundred eighteen million, five hundred twenty-two thousand, three hundred nine".