81787614437509 has 2 divisors, whose sum is σ = 81787614437510. Its totient is φ = 81787614437508.

The previous prime is 81787614437437. The next prime is 81787614437651. The reversal of 81787614437509 is 90573441678718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81761778697284 + 25835740225 = 9042222^2 + 160735^2 .

It is a cyclic number.

It is not a de Polignac number, because 81787614437509 - 2⁷ = 81787614437381 is a prime.

It is a super-2 number, since 2×81787614437509² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81787614437209) 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, 40893807218754 + 40893807218755.

It is an arithmetic number, because the mean of its divisors is an integer number (40893807218755).

Almost surely, 2^{81787614437509} is an apocalyptic number.

It is an amenable number.

81787614437509 is a deficient number, since it is larger than the sum of its proper divisors (1).

81787614437509 is an equidigital number, since it uses as much as digits as its factorization.

81787614437509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 284497920, while the sum is 70.

The spelling of 81787614437509 in words is "eighty-one trillion, seven hundred eighty-seven billion, six hundred fourteen million, four hundred thirty-seven thousand, five hundred nine".