9864991 has 4 divisors (see below), whose sum is σ = 9891400. Its totient is φ = 9838584.

The previous prime is 9864989. The next prime is 9865007. The reversal of 9864991 is 1994689.

9864991 = T₂₅₆₃ + T₂₅₆₄ + T₂₅₆₅.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1994689 = 577 ⋅3457.

It is a cyclic number.

It is not a de Polignac number, because 9864991 - 2¹ = 9864989 is a prime.

It is a Duffinian number.

9864991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9864091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12636 + ... + 13393.

It is an arithmetic number, because the mean of its divisors is an integer number (2472850).

Almost surely, 2^9864991 is an apocalyptic number.

9864991 is the 2565-th centered triangular number.

9864991 is a deficient number, since it is larger than the sum of its proper divisors (26409).

9864991 is a wasteful number, since it uses less digits than its factorization.

9864991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26408.

The product of its digits is 139968, while the sum is 46.

The square root of 9864991 is about 3140.8583221788. The cubic root of 9864991 is about 214.4695124231.

The spelling of 9864991 in words is "nine million, eight hundred sixty-four thousand, nine hundred ninety-one".