217998145 has 4 divisors (see below), whose sum is σ = 261597780. Its totient is φ = 174398512.

The previous prime is 217998139. The next prime is 217998149. The reversal of 217998145 is 541899712.

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 171321921 + 46676224 = 13089^2 + 6832^2 .

It is a cyclic number.

It is not a de Polignac number, because 217998145 - 2²⁵ = 184443713 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 217998095 and 217998104.

It is not an unprimeable number, because it can be changed into a prime (217998149) 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, 21799810 + ... + 21799819.

It is an arithmetic number, because the mean of its divisors is an integer number (65399445).

Almost surely, 2^217998145 is an apocalyptic number.

It is an amenable number.

217998145 is a deficient number, since it is larger than the sum of its proper divisors (43599635).

217998145 is an equidigital number, since it uses as much as digits as its factorization.

217998145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43599634.

The product of its digits is 181440, while the sum is 46.

The square root of 217998145 is about 14764.7602418732. The cubic root of 217998145 is about 601.8444584045.

The spelling of 217998145 in words is "two hundred seventeen million, nine hundred ninety-eight thousand, one hundred forty-five".