81377247689 has 2 divisors, whose sum is σ = 81377247690. Its totient is φ = 81377247688.

The previous prime is 81377247673. The next prime is 81377247713. The reversal of 81377247689 is 98674277318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73391144464 + 7986103225 = 270908^2 + 89365^2 .

It is a cyclic number.

It is not a de Polignac number, because 81377247689 - 2⁴ = 81377247673 is a prime.

It is not a weakly prime, because it can be changed into another prime (81377247629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40688623844 + 40688623845.

It is an arithmetic number, because the mean of its divisors is an integer number (40688623845).

Almost surely, 2^81377247689 is an apocalyptic number.

It is an amenable number.

81377247689 is a deficient number, since it is larger than the sum of its proper divisors (1).

81377247689 is an equidigital number, since it uses as much as digits as its factorization.

81377247689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28449792, while the sum is 62.

The spelling of 81377247689 in words is "eighty-one billion, three hundred seventy-seven million, two hundred forty-seven thousand, six hundred eighty-nine".