81598938077 has 2 divisors, whose sum is σ = 81598938078. Its totient is φ = 81598938076.

The previous prime is 81598938073. The next prime is 81598938097. The reversal of 81598938077 is 77083989518.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48814041721 + 32784896356 = 220939^2 + 181066^2 .

It is a cyclic number.

It is not a de Polignac number, because 81598938077 - 2² = 81598938073 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81598938073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40799469038 + 40799469039.

It is an arithmetic number, because the mean of its divisors is an integer number (40799469039).

Almost surely, 2^81598938077 is an apocalyptic number.

It is an amenable number.

81598938077 is a deficient number, since it is larger than the sum of its proper divisors (1).

81598938077 is an equidigital number, since it uses as much as digits as its factorization.

81598938077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30481920, while the sum is 65.

The spelling of 81598938077 in words is "eighty-one billion, five hundred ninety-eight million, nine hundred thirty-eight thousand, seventy-seven".