81965777 has 2 divisors, whose sum is σ = 81965778. Its totient is φ = 81965776.

The previous prime is 81965759. The next prime is 81965831. The reversal of 81965777 is 77756918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75620416 + 6345361 = 8696^2 + 2519^2 .

It is a cyclic number.

It is not a de Polignac number, because 81965777 - 2¹² = 81961681 is a prime.

It is not a weakly prime, because it can be changed into another prime (81964777) 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, 40982888 + 40982889.

It is an arithmetic number, because the mean of its divisors is an integer number (40982889).

Almost surely, 2^81965777 is an apocalyptic number.

It is an amenable number.

81965777 is a deficient number, since it is larger than the sum of its proper divisors (1).

81965777 is an equidigital number, since it uses as much as digits as its factorization.

81965777 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 740880, while the sum is 50.

The square root of 81965777 is about 9053.4952918748. The cubic root of 81965777 is about 434.3877006586.

The spelling of 81965777 in words is "eighty-one million, nine hundred sixty-five thousand, seven hundred seventy-seven".