216539261 has 2 divisors, whose sum is σ = 216539262. Its totient is φ = 216539260.

The previous prime is 216539231. The next prime is 216539303. The reversal of 216539261 is 162935612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 185123236 + 31416025 = 13606^2 + 5605^2 .

It is a cyclic number.

It is not a de Polignac number, because 216539261 - 2¹⁰ = 216538237 is a prime.

It is a super-2 number, since 2×216539261² = 93778503108852242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216539221) 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 as a sum of consecutive naturals, namely, 108269630 + 108269631.

It is an arithmetic number, because the mean of its divisors is an integer number (108269631).

Almost surely, 2^216539261 is an apocalyptic number.

It is an amenable number.

216539261 is a deficient number, since it is larger than the sum of its proper divisors (1).

216539261 is an equidigital number, since it uses as much as digits as its factorization.

216539261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19440, while the sum is 35.

The square root of 216539261 is about 14715.2730521727. The cubic root of 216539261 is about 600.4989007891.

The spelling of 216539261 in words is "two hundred sixteen million, five hundred thirty-nine thousand, two hundred sixty-one".