28861721729257 has 2 divisors, whose sum is σ = 28861721729258. Its totient is φ = 28861721729256.

The previous prime is 28861721729233. The next prime is 28861721729327. The reversal of 28861721729257 is 75292712716882.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27926828053056 + 934893676201 = 5284584^2 + 966899^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28861721729257 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 28861721729192 and 28861721729201.

It is not a weakly prime, because it can be changed into another prime (28861721729207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14430860864628 + 14430860864629.

It is an arithmetic number, because the mean of its divisors is an integer number (14430860864629).

Almost surely, 2^{28861721729257} is an apocalyptic number.

It is an amenable number.

28861721729257 is a deficient number, since it is larger than the sum of its proper divisors (1).

28861721729257 is an equidigital number, since it uses as much as digits as its factorization.

28861721729257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 94832640, while the sum is 67.

The spelling of 28861721729257 in words is "twenty-eight trillion, eight hundred sixty-one billion, seven hundred twenty-one million, seven hundred twenty-nine thousand, two hundred fifty-seven".