9991875 has 30 divisors (see below), whose sum is σ = 16878972. Its totient is φ = 5256000.

The previous prime is 9991847. The next prime is 9991879. The reversal of 9991875 is 5781999.

9991875 is digitally balanced in base 2, base 3 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 9991875 - 2⁶ = 9991811 is a prime.

Its product of digits (204120) is a multiple of the sum of its prime divisors (81).

It is not an unprimeable number, because it can be changed into a prime (9991879) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 136839 + ... + 136911.

Almost surely, 2^9991875 is an apocalyptic number.

9991875 is a deficient number, since it is larger than the sum of its proper divisors (6887097).

9991875 is an frugal number, since it uses more digits than its factorization.

9991875 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169 (or 81 counting only the distinct ones).

The product of its digits is 204120, while the sum is 48.

The square root of 9991875 is about 3160.9927238132. The cubic root of 9991875 is about 215.3851039203.

Multiplying 9991875 by its sum of digits (48), we get a square (479610000 = 21900²).

The spelling of 9991875 in words is "nine million, nine hundred ninety-one thousand, eight hundred seventy-five".