128772781 has 2 divisors, whose sum is σ = 128772782. Its totient is φ = 128772780.

The previous prime is 128772719. The next prime is 128772817. The reversal of 128772781 is 187277821.

Together with next prime (128772817) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76282756 + 52490025 = 8734^2 + 7245^2 .

It is an emirp because it is prime and its reverse (187277821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 128772781 - 2¹³ = 128764589 is a prime.

It is a super-2 number, since 2×128772781² = 33164858252947922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128712781) 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, 64386390 + 64386391.

It is an arithmetic number, because the mean of its divisors is an integer number (64386391).

Almost surely, 2^128772781 is an apocalyptic number.

It is an amenable number.

128772781 is a deficient number, since it is larger than the sum of its proper divisors (1).

128772781 is an equidigital number, since it uses as much as digits as its factorization.

128772781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 87808, while the sum is 43.

The square root of 128772781 is about 11347.8095243091. The cubic root of 128772781 is about 504.9805972351.

The spelling of 128772781 in words is "one hundred twenty-eight million, seven hundred seventy-two thousand, seven hundred eighty-one".