81007777 has 2 divisors, whose sum is σ = 81007778. Its totient is φ = 81007776.

The previous prime is 81007739. The next prime is 81007793. The reversal of 81007777 is 77770018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80353296 + 654481 = 8964^2 + 809^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81007777 is a prime.

It is not a weakly prime, because it can be changed into another prime (81007727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40503888 + 40503889.

It is an arithmetic number, because the mean of its divisors is an integer number (40503889).

Almost surely, 2^81007777 is an apocalyptic number.

It is an amenable number.

81007777 is a deficient number, since it is larger than the sum of its proper divisors (1).

81007777 is an equidigital number, since it uses as much as digits as its factorization.

81007777 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19208, while the sum is 37.

The square root of 81007777 is about 9000.4320451854. The cubic root of 81007777 is about 432.6887180255.

The spelling of 81007777 in words is "eighty-one million, seven thousand, seven hundred seventy-seven".