216669281 has 4 divisors (see below), whose sum is σ = 216754692. Its totient is φ = 216583872.

The previous prime is 216669227. The next prime is 216669287. The reversal of 216669281 is 182966612.

It is a happy number.

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 202350625 + 14318656 = 14225^2 + 3784^2 .

It is a cyclic number.

It is not a de Polignac number, because 216669281 - 2¹⁸ = 216407137 is a prime.

It is a super-2 number, since 2×216669281² = 93891154658113922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216669287) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38780 + ... + 44013.

It is an arithmetic number, because the mean of its divisors is an integer number (54188673).

Almost surely, 2^216669281 is an apocalyptic number.

It is an amenable number.

216669281 is a deficient number, since it is larger than the sum of its proper divisors (85411).

216669281 is an equidigital number, since it uses as much as digits as its factorization.

216669281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85410.

The product of its digits is 62208, while the sum is 41.

The square root of 216669281 is about 14719.6902480997. The cubic root of 216669281 is about 600.6190656728.

The spelling of 216669281 in words is "two hundred sixteen million, six hundred sixty-nine thousand, two hundred eighty-one".