216505549 has 4 divisors (see below), whose sum is σ = 233159836. Its totient is φ = 199851264.

The previous prime is 216505511. The next prime is 216505573. The reversal of 216505549 is 945505612.

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 86955625 + 129549924 = 9325^2 + 11382^2 .

It is a cyclic number.

It is not a de Polignac number, because 216505549 - 2¹⁹ = 215981261 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216505579) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8327124 + ... + 8327149.

It is an arithmetic number, because the mean of its divisors is an integer number (58289959).

Almost surely, 2^216505549 is an apocalyptic number.

It is an amenable number.

216505549 is a deficient number, since it is larger than the sum of its proper divisors (16654287).

216505549 is a wasteful number, since it uses less digits than its factorization.

216505549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16654286.

The product of its (nonzero) digits is 54000, while the sum is 37.

The square root of 216505549 is about 14714.1275310499. The cubic root of 216505549 is about 600.4677362026.

The spelling of 216505549 in words is "two hundred sixteen million, five hundred five thousand, five hundred forty-nine".