81677779061 has 2 divisors, whose sum is σ = 81677779062. Its totient is φ = 81677779060.

The previous prime is 81677778997. The next prime is 81677779087. The reversal of 81677779061 is 16097777618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51855942961 + 29821836100 = 227719^2 + 172690^2 .

It is a cyclic number.

It is not a de Polignac number, because 81677779061 - 2⁶ = 81677778997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81677773061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40838889530 + 40838889531.

It is an arithmetic number, because the mean of its divisors is an integer number (40838889531).

Almost surely, 2^81677779061 is an apocalyptic number.

It is an amenable number.

81677779061 is a deficient number, since it is larger than the sum of its proper divisors (1).

81677779061 is an equidigital number, since it uses as much as digits as its factorization.

81677779061 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6223392, while the sum is 59.

The spelling of 81677779061 in words is "eighty-one billion, six hundred seventy-seven million, seven hundred seventy-nine thousand, sixty-one".