8564721 has 8 divisors (see below), whose sum is σ = 12457824. Its totient is φ = 5190720.

The previous prime is 8564713. The next prime is 8564729. The reversal of 8564721 is 1274658.

It is an interprime number because it is at equal distance from previous prime (8564713) and next prime (8564729).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 8564721 - 2³ = 8564713 is a prime.

It is a super-3 number, since 3×8564721³ (a number of 22 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 259537 = 8564721 / (8 + 5 + 6 + 4 + 7 + 2 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8564729) 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 7 ways as a sum of consecutive naturals, for example, 129736 + ... + 129801.

It is an arithmetic number, because the mean of its divisors is an integer number (1557228).

Almost surely, 2^8564721 is an apocalyptic number.

It is an amenable number.

8564721 is a deficient number, since it is larger than the sum of its proper divisors (3893103).

8564721 is a wasteful number, since it uses less digits than its factorization.

8564721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 259551.

The product of its digits is 13440, while the sum is 33.

The square root of 8564721 is about 2926.5544587450. The cubic root of 8564721 is about 204.5994239991.

The spelling of 8564721 in words is "eight million, five hundred sixty-four thousand, seven hundred twenty-one".