216722261 has 16 divisors (see below), whose sum is σ = 259801344. Its totient is φ = 176757504.

The previous prime is 216722243. The next prime is 216722291. The reversal of 216722261 is 162227612.

It is a happy number.

It is not a de Polignac number, because 216722261 - 2¹⁰ = 216721237 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216722291) 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 15 ways as a sum of consecutive naturals, for example, 28301 + ... + 35133.

It is an arithmetic number, because the mean of its divisors is an integer number (16237584).

Almost surely, 2^216722261 is an apocalyptic number.

It is an amenable number.

216722261 is a deficient number, since it is larger than the sum of its proper divisors (43079083).

216722261 is a wasteful number, since it uses less digits than its factorization.

216722261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7060.

The product of its digits is 4032, while the sum is 29.

The square root of 216722261 is about 14721.4897683624. The cubic root of 216722261 is about 600.6680161665.

Adding to 216722261 its reverse (162227612), we get a palindrome (378949873).

The spelling of 216722261 in words is "two hundred sixteen million, seven hundred twenty-two thousand, two hundred sixty-one".