28057781 has 2 divisors, whose sum is σ = 28057782. Its totient is φ = 28057780.

The previous prime is 28057753. The next prime is 28057789. The reversal of 28057781 is 18775082.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23435281 + 4622500 = 4841^2 + 2150^2 .

It is a cyclic number.

It is not a de Polignac number, because 28057781 - 2⁶ = 28057717 is a prime.

It is a super-2 number, since 2×28057781² = 1574478149287922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28057789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14028890 + 14028891.

It is an arithmetic number, because the mean of its divisors is an integer number (14028891).

Almost surely, 2^28057781 is an apocalyptic number.

It is an amenable number.

28057781 is a deficient number, since it is larger than the sum of its proper divisors (1).

28057781 is an equidigital number, since it uses as much as digits as its factorization.

28057781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31360, while the sum is 38.

The square root of 28057781 is about 5296.9595996194. The cubic root of 28057781 is about 303.8676312281.

The spelling of 28057781 in words is "twenty-eight million, fifty-seven thousand, seven hundred eighty-one".