28078847921 has 2 divisors, whose sum is σ = 28078847922. Its totient is φ = 28078847920.

The previous prime is 28078847917. The next prime is 28078848019. The reversal of 28078847921 is 12974887082.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 26556287521 + 1522560400 = 162961^2 + 39020^2 .

It is a cyclic number.

It is not a de Polignac number, because 28078847921 - 2² = 28078847917 is a prime.

It is not a weakly prime, because it can be changed into another prime (28078847911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14039423960 + 14039423961.

It is an arithmetic number, because the mean of its divisors is an integer number (14039423961).

Almost surely, 2^28078847921 is an apocalyptic number.

It is an amenable number.

28078847921 is a deficient number, since it is larger than the sum of its proper divisors (1).

28078847921 is an equidigital number, since it uses as much as digits as its factorization.

28078847921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3612672, while the sum is 56.

The spelling of 28078847921 in words is "twenty-eight billion, seventy-eight million, eight hundred forty-seven thousand, nine hundred twenty-one".