81182742541 has 2 divisors, whose sum is σ = 81182742542. Its totient is φ = 81182742540.

The previous prime is 81182742503. The next prime is 81182742559. The reversal of 81182742541 is 14524728118.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78972802441 + 2209940100 = 281021^2 + 47010^2 .

It is a cyclic number.

It is not a de Polignac number, because 81182742541 - 2⁷ = 81182742413 is a prime.

It is a super-2 number, since 2×81182742541² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81182742581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40591371270 + 40591371271.

It is an arithmetic number, because the mean of its divisors is an integer number (40591371271).

Almost surely, 2^81182742541 is an apocalyptic number.

It is an amenable number.

81182742541 is a deficient number, since it is larger than the sum of its proper divisors (1).

81182742541 is an equidigital number, since it uses as much as digits as its factorization.

81182742541 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 143360, while the sum is 43.

The spelling of 81182742541 in words is "eighty-one billion, one hundred eighty-two million, seven hundred forty-two thousand, five hundred forty-one".