9865921 has 16 divisors (see below), whose sum is σ = 11390400. Its totient is φ = 8468928.

The previous prime is 9865907. The next prime is 9865927. The reversal of 9865921 is 1295689.

9865921 = T₁₅₀ + T₁₅₁ + ... + T₃₉₆.

It is not a de Polignac number, because 9865921 - 2²¹ = 7768769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9865927) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14235 + ... + 14911.

It is an arithmetic number, because the mean of its divisors is an integer number (711900).

Almost surely, 2^9865921 is an apocalyptic number.

It is an amenable number.

9865921 is a deficient number, since it is larger than the sum of its proper divisors (1524479).

9865921 is a wasteful number, since it uses less digits than its factorization.

9865921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768.

The product of its digits is 38880, while the sum is 40.

The square root of 9865921 is about 3141.0063673925. The cubic root of 9865921 is about 214.4762517562.

Subtracting from 9865921 its sum of digits (40), we obtain a square (9865881 = 3141²).

The spelling of 9865921 in words is "nine million, eight hundred sixty-five thousand, nine hundred twenty-one".