81688168106 has 8 divisors (see below), whose sum is σ = 122705078340. Its totient is φ = 40786475328.

The previous prime is 81688168097. The next prime is 81688168127. The reversal of 81688168106 is 60186188618.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 71187042481 + 10501125625 = 266809^2 + 102475^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28802591 + ... + 28805426.

Almost surely, 2^81688168106 is an apocalyptic number.

81688168106 is a deficient number, since it is larger than the sum of its proper divisors (41016910234).

81688168106 is a wasteful number, since it uses less digits than its factorization.

81688168106 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57608728.

The product of its (nonzero) digits is 884736, while the sum is 53.

The spelling of 81688168106 in words is "eighty-one billion, six hundred eighty-eight million, one hundred sixty-eight thousand, one hundred six".