28721685845969 has 2 divisors, whose sum is σ = 28721685845970. Its totient is φ = 28721685845968.

The previous prime is 28721685845939. The next prime is 28721685846031. The reversal of 28721685845969 is 96954858612782.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25683985435969 + 3037700410000 = 5067937^2 + 1742900^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28721685845969 is a prime.

It is a super-2 number, since 2×28721685845969² (a number of 28 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 28721685845893 and 28721685845902.

It is not a weakly prime, because it can be changed into another prime (28721685845939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14360842922984 + 14360842922985.

It is an arithmetic number, because the mean of its divisors is an integer number (14360842922985).

Almost surely, 2^{28721685845969} is an apocalyptic number.

It is an amenable number.

28721685845969 is a deficient number, since it is larger than the sum of its proper divisors (1).

28721685845969 is an equidigital number, since it uses as much as digits as its factorization.

28721685845969 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4180377600, while the sum is 80.

The spelling of 28721685845969 in words is "twenty-eight trillion, seven hundred twenty-one billion, six hundred eighty-five million, eight hundred forty-five thousand, nine hundred sixty-nine".