28721497309 has 2 divisors, whose sum is σ = 28721497310. Its totient is φ = 28721497308.

The previous prime is 28721497283. The next prime is 28721497327. The reversal of 28721497309 is 90379412782.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27981929284 + 739568025 = 167278^2 + 27195^2 .

It is a cyclic number.

It is not a de Polignac number, because 28721497309 - 2¹⁷ = 28721366237 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28721497379) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14360748654 + 14360748655.

It is an arithmetic number, because the mean of its divisors is an integer number (14360748655).

Almost surely, 2^28721497309 is an apocalyptic number.

It is an amenable number.

28721497309 is a deficient number, since it is larger than the sum of its proper divisors (1).

28721497309 is an equidigital number, since it uses as much as digits as its factorization.

28721497309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1524096, while the sum is 52.

The spelling of 28721497309 in words is "twenty-eight billion, seven hundred twenty-one million, four hundred ninety-seven thousand, three hundred nine".