8509921 has 4 divisors (see below), whose sum is σ = 9725632. Its totient is φ = 7294212.

The previous prime is 8509909. The next prime is 8509933. The reversal of 8509921 is 1299058.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1299058 = 2 ⋅649529.

It is an interprime number because it is at equal distance from previous prime (8509909) and next prime (8509933).

It is a cyclic number.

It is not a de Polignac number, because 8509921 - 2¹³ = 8501729 is a prime.

8509921 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (8509901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 607845 + ... + 607858.

It is an arithmetic number, because the mean of its divisors is an integer number (2431408).

Almost surely, 2^8509921 is an apocalyptic number.

It is an amenable number.

8509921 is a deficient number, since it is larger than the sum of its proper divisors (1215711).

8509921 is a wasteful number, since it uses less digits than its factorization.

8509921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1215710.

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 8509921 is about 2917.1768887059. The cubic root of 8509921 is about 204.1621244211.

The spelling of 8509921 in words is "eight million, five hundred nine thousand, nine hundred twenty-one".