9877991 has 4 divisors (see below), whose sum is σ = 9886800. Its totient is φ = 9869184.

The previous prime is 9877961. The next prime is 9877997. The reversal of 9877991 is 1997789.

9877991 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1997789 = 17 ⋅117517.

It is a cyclic number.

It is not a de Polignac number, because 9877991 - 2²² = 5683687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9877997) 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, 2426 + ... + 5063.

It is an arithmetic number, because the mean of its divisors is an integer number (2471700).

Almost surely, 2^9877991 is an apocalyptic number.

9877991 is a deficient number, since it is larger than the sum of its proper divisors (8809).

9877991 is a wasteful number, since it uses less digits than its factorization.

9877991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8808.

The product of its digits is 285768, while the sum is 50.

The square root of 9877991 is about 3142.9271388309. The cubic root of 9877991 is about 214.5636797618.

The spelling of 9877991 in words is "nine million, eight hundred seventy-seven thousand, nine hundred ninety-one".