81263661606 has 24 divisors (see below), whose sum is σ = 176085979680. Its totient is φ = 27085623696.

The previous prime is 81263661587. The next prime is 81263661649. The reversal of 81263661606 is 60616636218.

81263661606 is a `hidden beast` number, since 8 + 1 + 2 + 6 + 36 + 6 + 1 + 606 = 666.

It is a super-2 number, since 2×81263661606² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 in 11 ways as a sum of consecutive naturals, for example, 40275 + ... + 405153.

It is an arithmetic number, because the mean of its divisors is an integer number (7336915820).

Almost surely, 2^81263661606 is an apocalyptic number.

81263661606 is an abundant number, since it is smaller than the sum of its proper divisors (94822318074).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81263661606 is a wasteful number, since it uses less digits than its factorization.

81263661606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 377260 (or 377257 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 45.

The spelling of 81263661606 in words is "eighty-one billion, two hundred sixty-three million, six hundred sixty-one thousand, six hundred six".