81081779 has 2 divisors, whose sum is σ = 81081780. Its totient is φ = 81081778.

The previous prime is 81081773. The next prime is 81081817. The reversal of 81081779 is 97718018.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81081779 - 2²⁴ = 64304563 is a prime.

It is not a weakly prime, because it can be changed into another prime (81081773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40540889 + 40540890.

It is an arithmetic number, because the mean of its divisors is an integer number (40540890).

Almost surely, 2^81081779 is an apocalyptic number.

81081779 is a deficient number, since it is larger than the sum of its proper divisors (1).

81081779 is an equidigital number, since it uses as much as digits as its factorization.

81081779 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28224, while the sum is 41.

The square root of 81081779 is about 9004.5421316134. The cubic root of 81081779 is about 432.8204341250.

The spelling of 81081779 in words is "eighty-one million, eighty-one thousand, seven hundred seventy-nine".