28471309781 has 2 divisors, whose sum is σ = 28471309782. Its totient is φ = 28471309780.

The previous prime is 28471309777. The next prime is 28471309817. The reversal of 28471309781 is 18790317482.

It is a happy number.

Together with next prime (28471309817) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27710929156 + 760380625 = 166466^2 + 27575^2 .

It is a cyclic number.

It is not a de Polignac number, because 28471309781 - 2² = 28471309777 is a prime.

It is a super-2 number, since 2×28471309781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28471309771) 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, 14235654890 + 14235654891.

It is an arithmetic number, because the mean of its divisors is an integer number (14235654891).

Almost surely, 2^28471309781 is an apocalyptic number.

It is an amenable number.

28471309781 is a deficient number, since it is larger than the sum of its proper divisors (1).

28471309781 is an equidigital number, since it uses as much as digits as its factorization.

28471309781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 677376, while the sum is 50.

The spelling of 28471309781 in words is "twenty-eight billion, four hundred seventy-one million, three hundred nine thousand, seven hundred eighty-one".