81729266099705 has 32 divisors (see below), whose sum is σ = 112493676282624. Its totient is φ = 55839023974656.

The previous prime is 81729266099671. The next prime is 81729266099743. The reversal of 81729266099705 is 50799066292718.

It is a cyclic number.

It is not a de Polignac number, because 81729266099705 - 2³⁰ = 81728192357881 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 418076714 + ... + 418272156.

It is an arithmetic number, because the mean of its divisors is an integer number (3515427383832).

Almost surely, 2^{81729266099705} is an apocalyptic number.

It is an amenable number.

81729266099705 is a deficient number, since it is larger than the sum of its proper divisors (30764410182919).

81729266099705 is a wasteful number, since it uses less digits than its factorization.

81729266099705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238865.

The product of its (nonzero) digits is 205752960, while the sum is 71.

Adding to 81729266099705 its sum of digits (71), we get a square (81729266099776 = 9040424²).

The spelling of 81729266099705 in words is "eighty-one trillion, seven hundred twenty-nine billion, two hundred sixty-six million, ninety-nine thousand, seven hundred five".