9991864 has 24 divisors (see below), whose sum is σ = 19228680. Its totient is φ = 4867520.

The previous prime is 9991847. The next prime is 9991879. The reversal of 9991864 is 4681999.

9991864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13077 + ... + 13819.

It is an arithmetic number, because the mean of its divisors is an integer number (801195).

Almost surely, 2^9991864 is an apocalyptic number.

It is an amenable number.

9991864 is a deficient number, since it is larger than the sum of its proper divisors (9236816).

9991864 is a wasteful number, since it uses less digits than its factorization.

9991864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 831 (or 786 counting only the distinct ones).

The product of its digits is 139968, while the sum is 46.

The square root of 9991864 is about 3160.9909838530. The cubic root of 9991864 is about 215.3850248815.

The spelling of 9991864 in words is "nine million, nine hundred ninety-one thousand, eight hundred sixty-four".