81377831893 has 2 divisors, whose sum is σ = 81377831894. Its totient is φ = 81377831892.

The previous prime is 81377831803. The next prime is 81377831911. The reversal of 81377831893 is 39813877318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 67528778769 + 13849053124 = 259863^2 + 117682^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81377831893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81377831803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40688915946 + 40688915947.

It is an arithmetic number, because the mean of its divisors is an integer number (40688915947).

Almost surely, 2^81377831893 is an apocalyptic number.

It is an amenable number.

81377831893 is a deficient number, since it is larger than the sum of its proper divisors (1).

81377831893 is an equidigital number, since it uses as much as digits as its factorization.

81377831893 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6096384, while the sum is 58.

The spelling of 81377831893 in words is "eighty-one billion, three hundred seventy-seven million, eight hundred thirty-one thousand, eight hundred ninety-three".