86139821 has 2 divisors, whose sum is σ = 86139822. Its totient is φ = 86139820.

The previous prime is 86139751. The next prime is 86139839. The reversal of 86139821 is 12893168.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66015625 + 20124196 = 8125^2 + 4486^2 .

It is a cyclic number.

It is not a de Polignac number, because 86139821 - 2¹⁴ = 86123437 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 (86139841) 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, 43069910 + 43069911.

It is an arithmetic number, because the mean of its divisors is an integer number (43069911).

Almost surely, 2^86139821 is an apocalyptic number.

It is an amenable number.

86139821 is a deficient number, since it is larger than the sum of its proper divisors (1).

86139821 is an equidigital number, since it uses as much as digits as its factorization.

86139821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 38.

The square root of 86139821 is about 9281.1540769454. The cubic root of 86139821 is about 441.6395801276.

The spelling of 86139821 in words is "eighty-six million, one hundred thirty-nine thousand, eight hundred twenty-one".