216749 has 4 divisors (see below), whose sum is σ = 233436. Its totient is φ = 200064.

The previous prime is 216743. The next prime is 216751. The reversal of 216749 is 947612.

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 122500 + 94249 = 350^2 + 307^2 .

It is a cyclic number.

It is not a de Polignac number, because 216749 - 2⁸ = 216493 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216743) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8324 + ... + 8349.

It is an arithmetic number, because the mean of its divisors is an integer number (58359).

2²¹⁶⁷⁴⁹ is an apocalyptic number.

It is an amenable number.

216749 is a deficient number, since it is larger than the sum of its proper divisors (16687).

216749 is a wasteful number, since it uses less digits than its factorization.

216749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16686.

The product of its digits is 3024, while the sum is 29.

The square root of 216749 is about 465.5630999124. The cubic root of 216749 is about 60.0692718446.

The spelling of 216749 in words is "two hundred sixteen thousand, seven hundred forty-nine".