216820028609 has 2 divisors, whose sum is σ = 216820028610. Its totient is φ = 216820028608.

The previous prime is 216820028603. The next prime is 216820028671. The reversal of 216820028609 is 906820028612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 194169778609 + 22650250000 = 440647^2 + 150500^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216820028609 is a prime.

It is a Sophie Germain 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 216820028609.

It is not a weakly prime, because it can be changed into another prime (216820028603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108410014304 + 108410014305.

It is an arithmetic number, because the mean of its divisors is an integer number (108410014305).

Almost surely, 2^216820028609 is an apocalyptic number.

It is an amenable number.

216820028609 is a deficient number, since it is larger than the sum of its proper divisors (1).

216820028609 is an equidigital number, since it uses as much as digits as its factorization.

216820028609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 165888, while the sum is 44.

The spelling of 216820028609 in words is "two hundred sixteen billion, eight hundred twenty million, twenty-eight thousand, six hundred nine".