9991915 has 8 divisors (see below), whose sum is σ = 12016368. Its totient is φ = 7976160.

The previous prime is 9991879. The next prime is 9991939. The reversal of 9991915 is 5191999.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 9991915 - 2¹³ = 9983723 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 705 + ... + 4525.

It is an arithmetic number, because the mean of its divisors is an integer number (1502046).

Almost surely, 2^9991915 is an apocalyptic number.

9991915 is a deficient number, since it is larger than the sum of its proper divisors (2024453).

9991915 is a wasteful number, since it uses less digits than its factorization.

9991915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4349.

The product of its digits is 32805, while the sum is 43.

The square root of 9991915 is about 3160.9990509331. Note that the first 3 decimals coincide. The cubic root of 9991915 is about 215.3853913335.

The spelling of 9991915 in words is "nine million, nine hundred ninety-one thousand, nine hundred fifteen".