81081773 has 2 divisors, whose sum is σ = 81081774. Its totient is φ = 81081772.

The previous prime is 81081769. The next prime is 81081779. The reversal of 81081773 is 37718018.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61748164 + 19333609 = 7858^2 + 4397^2 .

It is a cyclic number.

It is not a de Polignac number, because 81081773 - 2² = 81081769 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81081779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40540886 + 40540887.

It is an arithmetic number, because the mean of its divisors is an integer number (40540887).

Almost surely, 2^81081773 is an apocalyptic number.

It is an amenable number.

81081773 is a deficient number, since it is larger than the sum of its proper divisors (1).

81081773 is an equidigital number, since it uses as much as digits as its factorization.

81081773 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9408, while the sum is 35.

The square root of 81081773 is about 9004.5417984482. The cubic root of 81081773 is about 432.8204234488.

The spelling of 81081773 in words is "eighty-one million, eighty-one thousand, seven hundred seventy-three".