28689662021 has 2 divisors, whose sum is σ = 28689662022. Its totient is φ = 28689662020.

The previous prime is 28689661969. The next prime is 28689662033. The reversal of 28689662021 is 12026698682.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27793557796 + 896104225 = 166714^2 + 29935^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28689662021 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28689862021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14344831010 + 14344831011.

It is an arithmetic number, because the mean of its divisors is an integer number (14344831011).

Almost surely, 2^28689662021 is an apocalyptic number.

It is an amenable number.

28689662021 is a deficient number, since it is larger than the sum of its proper divisors (1).

28689662021 is an equidigital number, since it uses as much as digits as its factorization.

28689662021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 995328, while the sum is 50.

The spelling of 28689662021 in words is "twenty-eight billion, six hundred eighty-nine million, six hundred sixty-two thousand, twenty-one".