9991923 has 4 divisors (see below), whose sum is σ = 13322568. Its totient is φ = 6661280.

The previous prime is 9991879. The next prime is 9991939. The reversal of 9991923 is 3291999.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 9991923 - 2¹⁰ = 9990899 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9991963) 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, 1665318 + ... + 1665323.

It is an arithmetic number, because the mean of its divisors is an integer number (3330642).

Almost surely, 2^9991923 is an apocalyptic number.

9991923 is a deficient number, since it is larger than the sum of its proper divisors (3330645).

9991923 is a wasteful number, since it uses less digits than its factorization.

9991923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3330644.

The product of its digits is 39366, while the sum is 42.

The square root of 9991923 is about 3161.0003163556. Note that the first 3 decimals coincide. The cubic root of 9991923 is about 215.3854488161.

It can be divided in two parts, 999192 and 3, that multiplied together give a triangular number (2997576 = T₂₄₄₈).

The spelling of 9991923 in words is "nine million, nine hundred ninety-one thousand, nine hundred twenty-three".