9991220001 has 24 divisors (see below), whose sum is σ = 15915421440. Its totient is φ = 5554960992.

The previous prime is 9991219943. The next prime is 9991220009. The reversal of 9991220001 is 1000221999.

It is not a de Polignac number, because 9991220001 - 2⁶ = 9991219937 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9991220009) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 913041 + ... + 923918.

It is an arithmetic number, because the mean of its divisors is an integer number (663142560).

Almost surely, 2^9991220001 is an apocalyptic number.

It is an amenable number.

9991220001 is a deficient number, since it is larger than the sum of its proper divisors (5924201439).

9991220001 is a wasteful number, since it uses less digits than its factorization.

9991220001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1837013 (or 1837006 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 33.

The square root of 9991220001 is about 99956.0903647196. The cubic root of 9991220001 is about 2153.8039742589.

The spelling of 9991220001 in words is "nine billion, nine hundred ninety-one million, two hundred twenty thousand, one".