216679409 has 2 divisors, whose sum is σ = 216679410. Its totient is φ = 216679408.

The previous prime is 216679391. The next prime is 216679453. The reversal of 216679409 is 904976612.

It is an a-pointer prime, because the next prime (216679453) can be obtained adding 216679409 to its sum of digits (44).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 144480400 + 72199009 = 12020^2 + 8497^2 .

It is a cyclic number.

It is not a de Polignac number, because 216679409 - 2¹² = 216675313 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 216679409.

It is not a weakly prime, because it can be changed into another prime (216679459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108339704 + 108339705.

It is an arithmetic number, because the mean of its divisors is an integer number (108339705).

Almost surely, 2^216679409 is an apocalyptic number.

It is an amenable number.

216679409 is a deficient number, since it is larger than the sum of its proper divisors (1).

216679409 is an equidigital number, since it uses as much as digits as its factorization.

216679409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 163296, while the sum is 44.

The square root of 216679409 is about 14720.0342730579. The cubic root of 216679409 is about 600.6284239831.

The spelling of 216679409 in words is "two hundred sixteen million, six hundred seventy-nine thousand, four hundred nine".