91721310166605 has 32 divisors (see below), whose sum is σ = 168747917912064. Its totient is φ = 41672504102976.

The previous prime is 91721310166601. The next prime is 91721310166627. The reversal of 91721310166605 is 50666101312719.

It is a happy number.

It is not a de Polignac number, because 91721310166605 - 2² = 91721310166601 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91721310166601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2679542049 + ... + 2679576278.

It is an arithmetic number, because the mean of its divisors is an integer number (5273372434752).

Almost surely, 2^{91721310166605} is an apocalyptic number.

It is an amenable number.

91721310166605 is a deficient number, since it is larger than the sum of its proper divisors (77026607745459).

91721310166605 is a wasteful number, since it uses less digits than its factorization.

91721310166605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5359118505.

The product of its (nonzero) digits is 408240, while the sum is 48.

The spelling of 91721310166605 in words is "ninety-one trillion, seven hundred twenty-one billion, three hundred ten million, one hundred sixty-six thousand, six hundred five".