216985261 has 2 divisors, whose sum is σ = 216985262. Its totient is φ = 216985260.

The previous prime is 216985253. The next prime is 216985283. The reversal of 216985261 is 162589612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 142922025 + 74063236 = 11955^2 + 8606^2 .

It is a cyclic number.

It is not a de Polignac number, because 216985261 - 2³ = 216985253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216985361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108492630 + 108492631.

It is an arithmetic number, because the mean of its divisors is an integer number (108492631).

Almost surely, 2^216985261 is an apocalyptic number.

It is an amenable number.

216985261 is a deficient number, since it is larger than the sum of its proper divisors (1).

216985261 is an equidigital number, since it uses as much as digits as its factorization.

216985261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 40.

The square root of 216985261 is about 14730.4195799034. The cubic root of 216985261 is about 600.9108951207.

The spelling of 216985261 in words is "two hundred sixteen million, nine hundred eighty-five thousand, two hundred sixty-one".