28187442821 has 2 divisors, whose sum is σ = 28187442822. Its totient is φ = 28187442820.

The previous prime is 28187442809. The next prime is 28187442919. The reversal of 28187442821 is 12824478182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27502573921 + 684868900 = 165839^2 + 26170^2 .

It is a cyclic number.

It is not a de Polignac number, because 28187442821 - 2¹⁰ = 28187441797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28187402821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14093721410 + 14093721411.

It is an arithmetic number, because the mean of its divisors is an integer number (14093721411).

Almost surely, 2^28187442821 is an apocalyptic number.

It is an amenable number.

28187442821 is a deficient number, since it is larger than the sum of its proper divisors (1).

28187442821 is an equidigital number, since it uses as much as digits as its factorization.

28187442821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 458752, while the sum is 47.

The spelling of 28187442821 in words is "twenty-eight billion, one hundred eighty-seven million, four hundred forty-two thousand, eight hundred twenty-one".