81983778705 has 12 divisors (see below), whose sum is σ = 142105216500. Its totient is φ = 43724681952.

The previous prime is 81983778683. The next prime is 81983778727. The reversal of 81983778705 is 50787738918.

81983778705 is a `hidden beast` number, since 8 + 198 + 377 + 8 + 70 + 5 = 666.

It is an interprime number because it is at equal distance from previous prime (81983778683) and next prime (81983778727).

It can be written as a sum of positive squares in 2 ways, for example, as 13153107969 + 68830670736 = 114687^2 + 262356^2 .

It is not a de Polignac number, because 81983778705 - 2⁶ = 81983778641 is a prime.

It is a super-2 number, since 2×81983778705² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

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 in 11 ways as a sum of consecutive naturals, for example, 910930830 + ... + 910930919.

It is an arithmetic number, because the mean of its divisors is an integer number (11842101375).

Almost surely, 2^81983778705 is an apocalyptic number.

It is an amenable number.

81983778705 is a deficient number, since it is larger than the sum of its proper divisors (60121437795).

81983778705 is a wasteful number, since it uses less digits than its factorization.

81983778705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1821861760 (or 1821861757 counting only the distinct ones).

The product of its (nonzero) digits is 23708160, while the sum is 63.

The spelling of 81983778705 in words is "eighty-one billion, nine hundred eighty-three million, seven hundred seventy-eight thousand, seven hundred five".