8209613821 has 2 divisors, whose sum is σ = 8209613822. Its totient is φ = 8209613820.

The previous prime is 8209613807. The next prime is 8209613831. The reversal of 8209613821 is 1283169028.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4867155225 + 3342458596 = 69765^2 + 57814^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8209613821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8209613801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4104806910 + 4104806911.

It is an arithmetic number, because the mean of its divisors is an integer number (4104806911).

Almost surely, 2^8209613821 is an apocalyptic number.

It is an amenable number.

8209613821 is a deficient number, since it is larger than the sum of its proper divisors (1).

8209613821 is an equidigital number, since it uses as much as digits as its factorization.

8209613821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 41472, while the sum is 40.

The square root of 8209613821 is about 90606.9192777240. The cubic root of 8209613821 is about 2017.3174387910.

The spelling of 8209613821 in words is "eight billion, two hundred nine million, six hundred thirteen thousand, eight hundred twenty-one".