28318207921 has 2 divisors, whose sum is σ = 28318207922. Its totient is φ = 28318207920.

The previous prime is 28318207903. The next prime is 28318207933. The reversal of 28318207921 is 12970281382.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23441141025 + 4877066896 = 153105^2 + 69836^2 .

It is a cyclic number.

It is not a de Polignac number, because 28318207921 - 2¹⁹ = 28317683633 is a prime.

It is not a weakly prime, because it can be changed into another prime (28318207901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14159103960 + 14159103961.

It is an arithmetic number, because the mean of its divisors is an integer number (14159103961).

Almost surely, 2^28318207921 is an apocalyptic number.

It is an amenable number.

28318207921 is a deficient number, since it is larger than the sum of its proper divisors (1).

28318207921 is an equidigital number, since it uses as much as digits as its factorization.

28318207921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96768, while the sum is 43.

The spelling of 28318207921 in words is "twenty-eight billion, three hundred eighteen million, two hundred seven thousand, nine hundred twenty-one".