81351101989 has 2 divisors, whose sum is σ = 81351101990. Its totient is φ = 81351101988.

The previous prime is 81351101987. The next prime is 81351102029. The reversal of 81351101989 is 98910115318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 40817333089 + 40533768900 = 202033^2 + 201330^2 .

It is a cyclic number.

It is not a de Polignac number, because 81351101989 - 2¹ = 81351101987 is a prime.

It is a super-2 number, since 2×81351101989² (a number of 23 digits) contains 22 as substring.

Together with 81351101987, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81351101987) 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, 40675550994 + 40675550995.

It is an arithmetic number, because the mean of its divisors is an integer number (40675550995).

Almost surely, 2^81351101989 is an apocalyptic number.

It is an amenable number.

81351101989 is a deficient number, since it is larger than the sum of its proper divisors (1).

81351101989 is an equidigital number, since it uses as much as digits as its factorization.

81351101989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 77760, while the sum is 46.

The spelling of 81351101989 in words is "eighty-one billion, three hundred fifty-one million, one hundred one thousand, nine hundred eighty-nine".