81381285077 has 2 divisors, whose sum is σ = 81381285078. Its totient is φ = 81381285076.

The previous prime is 81381284921. The next prime is 81381285079. The reversal of 81381285077 is 77058218318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72017626321 + 9363658756 = 268361^2 + 96766^2 .

It is a cyclic number.

It is not a de Polignac number, because 81381285077 - 2¹⁴ = 81381268693 is a prime.

Together with 81381285079, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81381285079) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40690642538 + 40690642539.

It is an arithmetic number, because the mean of its divisors is an integer number (40690642539).

Almost surely, 2^81381285077 is an apocalyptic number.

It is an amenable number.

81381285077 is a deficient number, since it is larger than the sum of its proper divisors (1).

81381285077 is an equidigital number, since it uses as much as digits as its factorization.

81381285077 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 752640, while the sum is 50.

The spelling of 81381285077 in words is "eighty-one billion, three hundred eighty-one million, two hundred eighty-five thousand, seventy-seven".