10509721 has 4 divisors (see below), whose sum is σ = 10517092. Its totient is φ = 10502352.

The previous prime is 10509703. The next prime is 10509773. The reversal of 10509721 is 12790501.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 6553600 + 3956121 = 2560^2 + 1989^2 .

It is a cyclic number.

It is not a de Polignac number, because 10509721 - 2¹⁹ = 9985433 is a prime.

It is a super-4 number, since 4×10509721⁴ (a number of 29 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (10509701) 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, 786 + ... + 4651.

It is an arithmetic number, because the mean of its divisors is an integer number (2629273).

Almost surely, 2^10509721 is an apocalyptic number.

It is an amenable number.

10509721 is a deficient number, since it is larger than the sum of its proper divisors (7371).

10509721 is an equidigital number, since it uses as much as digits as its factorization.

10509721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7370.

The product of its (nonzero) digits is 630, while the sum is 25.

The square root of 10509721 is about 3241.8699850549. The cubic root of 10509721 is about 219.0435128262.

The spelling of 10509721 in words is "ten million, five hundred nine thousand, seven hundred twenty-one".