9991213 has 4 divisors (see below), whose sum is σ = 10203840. Its totient is φ = 9778588.

The previous prime is 9991211. The next prime is 9991259. The reversal of 9991213 is 3121999.

9991213 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 9991213 - 2¹ = 9991211 is a prime.

It is a super-2 number, since 2×9991213² = 199648674422738, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9991211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106243 + ... + 106336.

It is an arithmetic number, because the mean of its divisors is an integer number (2550960).

Almost surely, 2^9991213 is an apocalyptic number.

It is an amenable number.

9991213 is a deficient number, since it is larger than the sum of its proper divisors (212627).

9991213 is a wasteful number, since it uses less digits than its factorization.

9991213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212626.

The product of its digits is 4374, while the sum is 34.

The square root of 9991213 is about 3160.8880081395. Note that the first 3 decimals coincide. The cubic root of 9991213 is about 215.3803471191.

The spelling of 9991213 in words is "nine million, nine hundred ninety-one thousand, two hundred thirteen".