81205345619 has 2 divisors, whose sum is σ = 81205345620. Its totient is φ = 81205345618.

The previous prime is 81205345607. The next prime is 81205345633. The reversal of 81205345619 is 91654350218.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81205345619 - 2⁴ = 81205345603 is a prime.

It is a super-2 number, since 2×81205345619² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81205345619.

It is not a weakly prime, because it can be changed into another prime (81205345519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40602672809 + 40602672810.

It is an arithmetic number, because the mean of its divisors is an integer number (40602672810).

Almost surely, 2^81205345619 is an apocalyptic number.

81205345619 is a deficient number, since it is larger than the sum of its proper divisors (1).

81205345619 is an equidigital number, since it uses as much as digits as its factorization.

81205345619 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 259200, while the sum is 44.

The spelling of 81205345619 in words is "eighty-one billion, two hundred five million, three hundred forty-five thousand, six hundred nineteen".