91721122211 has 4 divisors (see below), whose sum is σ = 92532813672. Its totient is φ = 90909430752.

The previous prime is 91721122153. The next prime is 91721122243. The reversal of 91721122211 is 11222112719.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 91721122211 - 2¹⁰ = 91721121187 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91721142211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 405845561 + ... + 405845786.

It is an arithmetic number, because the mean of its divisors is an integer number (23133203418).

Almost surely, 2^91721122211 is an apocalyptic number.

91721122211 is a deficient number, since it is larger than the sum of its proper divisors (811691461).

91721122211 is a wasteful number, since it uses less digits than its factorization.

91721122211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811691460.

The product of its digits is 1008, while the sum is 29.

The spelling of 91721122211 in words is "ninety-one billion, seven hundred twenty-one million, one hundred twenty-two thousand, two hundred eleven".