9991212221001 has 16 divisors (see below), whose sum is σ = 14628915191808. Its totient is φ = 6015178938000.

The previous prime is 9991212220993. The next prime is 9991212221057. The reversal of 9991212221001 is 1001222121999.

It is a happy number.

It is not a de Polignac number, because 9991212221001 - 2³ = 9991212220993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9991212226001) 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, 1002524841 + ... + 1002534806.

It is an arithmetic number, because the mean of its divisors is an integer number (914307199488).

Almost surely, 2^{9991212221001} is an apocalyptic number.

It is an amenable number.

9991212221001 is a deficient number, since it is larger than the sum of its proper divisors (4637702970807).

9991212221001 is a wasteful number, since it uses less digits than its factorization.

9991212221001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2005059812.

The product of its (nonzero) digits is 11664, while the sum is 39.

The spelling of 9991212221001 in words is "nine trillion, nine hundred ninety-one billion, two hundred twelve million, two hundred twenty-one thousand, one".