16865244821 has 2 divisors, whose sum is σ = 16865244822. Its totient is φ = 16865244820.

The previous prime is 16865244793. The next prime is 16865244899. The reversal of 16865244821 is 12844256861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9270993796 + 7594251025 = 96286^2 + 87145^2 .

It is a cyclic number.

It is not a de Polignac number, because 16865244821 - 2¹⁰ = 16865243797 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16865244521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8432622410 + 8432622411.

It is an arithmetic number, because the mean of its divisors is an integer number (8432622411).

Almost surely, 2^16865244821 is an apocalyptic number.

It is an amenable number.

16865244821 is a deficient number, since it is larger than the sum of its proper divisors (1).

16865244821 is an equidigital number, since it uses as much as digits as its factorization.

16865244821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 737280, while the sum is 47.

The spelling of 16865244821 in words is "sixteen billion, eight hundred sixty-five million, two hundred forty-four thousand, eight hundred twenty-one".