218291945 has 12 divisors (see below), whose sum is σ = 263371404. Its totient is φ = 173690880.

The previous prime is 218291933. The next prime is 218291993. The reversal of 218291945 is 549192812.

It can be written as a sum of positive squares in 6 ways, for example, as 100721296 + 117570649 = 10036^2 + 10843^2 .

It is not a de Polignac number, because 218291945 - 2⁶ = 218291881 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 329915 + ... + 330575.

It is an arithmetic number, because the mean of its divisors is an integer number (21947617).

Almost surely, 2^218291945 is an apocalyptic number.

It is an amenable number.

218291945 is a deficient number, since it is larger than the sum of its proper divisors (45079459).

218291945 is an frugal number, since it uses more digits than its factorization.

218291945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1180 (or 923 counting only the distinct ones).

The product of its digits is 51840, while the sum is 41.

The square root of 218291945 is about 14774.7062576553. The cubic root of 218291945 is about 602.1147092147.

The spelling of 218291945 in words is "two hundred eighteen million, two hundred ninety-one thousand, nine hundred forty-five".