81130719977 has 2 divisors, whose sum is σ = 81130719978. Its totient is φ = 81130719976.

The previous prime is 81130719973. The next prime is 81130719997. The reversal of 81130719977 is 77991703118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73403606761 + 7727113216 = 270931^2 + 87904^2 .

It is a cyclic number.

It is not a de Polignac number, because 81130719977 - 2² = 81130719973 is a prime.

It is not a weakly prime, because it can be changed into another prime (81130719973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40565359988 + 40565359989.

It is an arithmetic number, because the mean of its divisors is an integer number (40565359989).

Almost surely, 2^81130719977 is an apocalyptic number.

It is an amenable number.

81130719977 is a deficient number, since it is larger than the sum of its proper divisors (1).

81130719977 is an equidigital number, since it uses as much as digits as its factorization.

81130719977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 666792, while the sum is 53.

The spelling of 81130719977 in words is "eighty-one billion, one hundred thirty million, seven hundred nineteen thousand, nine hundred seventy-seven".