91021212211 has 16 divisors (see below), whose sum is σ = 93387888000. Its totient is φ = 88666260480.

The previous prime is 91021212209. The next prime is 91021212259. The reversal of 91021212211 is 11221212019.

It is a cyclic number.

It is not a de Polignac number, because 91021212211 - 2¹ = 91021212209 is a prime.

It is a super-2 number, since 2×91021212211² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91021212811) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41315836 + ... + 41318038.

It is an arithmetic number, because the mean of its divisors is an integer number (5836743000).

Almost surely, 2^91021212211 is an apocalyptic number.

91021212211 is a deficient number, since it is larger than the sum of its proper divisors (2366675789).

91021212211 is a wasteful number, since it uses less digits than its factorization.

91021212211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4386.

The product of its (nonzero) digits is 144, while the sum is 22.

The spelling of 91021212211 in words is "ninety-one billion, twenty-one million, two hundred twelve thousand, two hundred eleven".