9959991 has 4 divisors (see below), whose sum is σ = 13279992. Its totient is φ = 6639992.

The previous prime is 9959987. The next prime is 9960023. The reversal of 9959991 is 1999599.

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 9959991 - 2² = 9959987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9959981) 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, 1659996 + ... + 1660001.

It is an arithmetic number, because the mean of its divisors is an integer number (3319998).

Almost surely, 2^9959991 is an apocalyptic number.

9959991 is a deficient number, since it is larger than the sum of its proper divisors (3320001).

9959991 is a wasteful number, since it uses less digits than its factorization.

9959991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3320000.

The product of its digits is 295245, while the sum is 51.

The square root of 9959991 is about 3155.9453417320. The cubic root of 9959991 is about 215.1557623745.

The spelling of 9959991 in words is "nine million, nine hundred fifty-nine thousand, nine hundred ninety-one".