216518761 has 2 divisors, whose sum is σ = 216518762. Its totient is φ = 216518760.

The previous prime is 216518759. The next prime is 216518777. The reversal of 216518761 is 167815612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 156750400 + 59768361 = 12520^2 + 7731^2 .

It is a cyclic number.

It is not a de Polignac number, because 216518761 - 2¹ = 216518759 is a prime.

Together with 216518759, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 216518761.

It is not a weakly prime, because it can be changed into another prime (216518161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108259380 + 108259381.

It is an arithmetic number, because the mean of its divisors is an integer number (108259381).

Almost surely, 2^216518761 is an apocalyptic number.

It is an amenable number.

216518761 is a deficient number, since it is larger than the sum of its proper divisors (1).

216518761 is an equidigital number, since it uses as much as digits as its factorization.

216518761 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 37.

The square root of 216518761 is about 14714.5764804836. The cubic root of 216518761 is about 600.4799502365.

The spelling of 216518761 in words is "two hundred sixteen million, five hundred eighteen thousand, seven hundred sixty-one".