8729721 has 128 divisors (see below), whose sum is σ = 19353600. Its totient is φ = 3732480.

The previous prime is 8729717. The next prime is 8729729. The reversal of 8729721 is 1279278.

It is not a de Polignac number, because 8729721 - 2² = 8729717 is a prime.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (8729729) 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 127 ways as a sum of consecutive naturals, for example, 459450 + ... + 459468.

It is an arithmetic number, because the mean of its divisors is an integer number (151200).

Almost surely, 2^8729721 is an apocalyptic number.

It is an amenable number.

8729721 is an abundant number, since it is smaller than the sum of its proper divisors (10623879).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

8729721 is a wasteful number, since it uses less digits than its factorization.

8729721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76 (or 70 counting only the distinct ones).

The product of its digits is 14112, while the sum is 36.

The square root of 8729721 is about 2954.6101265649. The cubic root of 8729721 is about 205.9049503376.

The spelling of 8729721 in words is "eight million, seven hundred twenty-nine thousand, seven hundred twenty-one".