216646649 has 2 divisors, whose sum is σ = 216646650. Its totient is φ = 216646648.

The previous prime is 216646609. The next prime is 216646663. The reversal of 216646649 is 946646612.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 199713424 + 16933225 = 14132^2 + 4115^2 .

It is a cyclic number.

It is not a de Polignac number, because 216646649 - 2²⁴ = 199869433 is a prime.

It is not a weakly prime, because it can be changed into another prime (216646609) 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 as a sum of consecutive naturals, namely, 108323324 + 108323325.

It is an arithmetic number, because the mean of its divisors is an integer number (108323325).

Almost surely, 2^216646649 is an apocalyptic number.

It is an amenable number.

216646649 is a deficient number, since it is larger than the sum of its proper divisors (1).

216646649 is an equidigital number, since it uses as much as digits as its factorization.

216646649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 373248, while the sum is 44.

The square root of 216646649 is about 14718.9214618463. The cubic root of 216646649 is about 600.5981525651.

The spelling of 216646649 in words is "two hundred sixteen million, six hundred forty-six thousand, six hundred forty-nine".