81563570793 has 12 divisors (see below), whose sum is σ = 117816573940. Its totient is φ = 54374547456.

The previous prime is 81563570791. The next prime is 81563570831. The reversal of 81563570793 is 39707536518.

81563570793 is a `hidden beast` number, since 8 + 1 + 5 + 63 + 570 + 7 + 9 + 3 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 19190006784 + 62373564009 = 138528^2 + 249747^2 .

It is not a de Polignac number, because 81563570793 - 2¹ = 81563570791 is a prime.

It is a super-3 number, since 3×81563570793³ (a number of 34 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81563570791) 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 in 11 ways as a sum of consecutive naturals, for example, 639705 + ... + 756537.

Almost surely, 2^81563570793 is an apocalyptic number.

It is an amenable number.

81563570793 is a deficient number, since it is larger than the sum of its proper divisors (36253003147).

81563570793 is a wasteful number, since it uses less digits than its factorization.

81563570793 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194408 (or 194405 counting only the distinct ones).

The product of its (nonzero) digits is 4762800, while the sum is 54.

The spelling of 81563570793 in words is "eighty-one billion, five hundred sixty-three million, five hundred seventy thousand, seven hundred ninety-three".