81758779 has 2 divisors, whose sum is σ = 81758780. Its totient is φ = 81758778.

The previous prime is 81758771. The next prime is 81758783. The reversal of 81758779 is 97785718.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81758779 - 2³ = 81758771 is a prime.

It is not a weakly prime, because it can be changed into another prime (81758771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40879389 + 40879390.

It is an arithmetic number, because the mean of its divisors is an integer number (40879390).

Almost surely, 2^81758779 is an apocalyptic number.

81758779 is a deficient number, since it is larger than the sum of its proper divisors (1).

81758779 is an equidigital number, since it uses as much as digits as its factorization.

81758779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 987840, while the sum is 52.

The square root of 81758779 is about 9042.0561267889. The cubic root of 81758779 is about 434.0217219620.

The spelling of 81758779 in words is "eighty-one million, seven hundred fifty-eight thousand, seven hundred seventy-nine".