81372801673 has 2 divisors, whose sum is σ = 81372801674. Its totient is φ = 81372801672.

The previous prime is 81372801667. The next prime is 81372801733. The reversal of 81372801673 is 37610827318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78384320784 + 2988480889 = 279972^2 + 54667^2 .

It is a cyclic number.

It is not a de Polignac number, because 81372801673 - 2⁵ = 81372801641 is a prime.

It is a super-2 number, since 2×81372801673² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81372801973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40686400836 + 40686400837.

It is an arithmetic number, because the mean of its divisors is an integer number (40686400837).

Almost surely, 2^81372801673 is an apocalyptic number.

It is an amenable number.

81372801673 is a deficient number, since it is larger than the sum of its proper divisors (1).

81372801673 is an equidigital number, since it uses as much as digits as its factorization.

81372801673 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 338688, while the sum is 46.

The spelling of 81372801673 in words is "eighty-one billion, three hundred seventy-two million, eight hundred one thousand, six hundred seventy-three".