991022122121 has 4 divisors (see below), whose sum is σ = 1043181181200. Its totient is φ = 938863063044.

The previous prime is 991022122087. The next prime is 991022122141. The reversal of 991022122121 is 121221220199.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991022122121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991022122141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26079529511 + ... + 26079529548.

It is an arithmetic number, because the mean of its divisors is an integer number (260795295300).

Almost surely, 2^991022122121 is an apocalyptic number.

It is an amenable number.

991022122121 is a deficient number, since it is larger than the sum of its proper divisors (52159059079).

991022122121 is a wasteful number, since it uses less digits than its factorization.

991022122121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52159059078.

The product of its (nonzero) digits is 2592, while the sum is 32.

The spelling of 991022122121 in words is "nine hundred ninety-one billion, twenty-two million, one hundred twenty-two thousand, one hundred twenty-one".