81789079 has 2 divisors, whose sum is σ = 81789080. Its totient is φ = 81789078.

The previous prime is 81789073. The next prime is 81789083. The reversal of 81789079 is 97098718.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81789079 - 2¹³ = 81780887 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81789073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40894539 + 40894540.

It is an arithmetic number, because the mean of its divisors is an integer number (40894540).

Almost surely, 2^81789079 is an apocalyptic number.

81789079 is a deficient number, since it is larger than the sum of its proper divisors (1).

81789079 is an equidigital number, since it uses as much as digits as its factorization.

81789079 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 254016, while the sum is 49.

The square root of 81789079 is about 9043.7314754475. The cubic root of 81789079 is about 434.0753318377.

The spelling of 81789079 in words is "eighty-one million, seven hundred eighty-nine thousand, seventy-nine".