9958791221 has 4 divisors (see below), whose sum is σ = 9959239200. Its totient is φ = 9958343244.

The previous prime is 9958791163. The next prime is 9958791251. The reversal of 9958791221 is 1221978599.

It is a happy number.

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 not a de Polignac number, because 9958791221 - 2¹⁰ = 9958790197 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9958791251) 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, 188801 + ... + 235718.

It is an arithmetic number, because the mean of its divisors is an integer number (2489809800).

Almost surely, 2^9958791221 is an apocalyptic number.

It is an amenable number.

9958791221 is a deficient number, since it is larger than the sum of its proper divisors (447979).

9958791221 is a wasteful number, since it uses less digits than its factorization.

9958791221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 447978.

The product of its digits is 816480, while the sum is 53.

The square root of 9958791221 is about 99793.7433960667. The cubic root of 9958791221 is about 2151.4712281746.

The spelling of 9958791221 in words is "nine billion, nine hundred fifty-eight million, seven hundred ninety-one thousand, two hundred twenty-one".