8723721 has 4 divisors (see below), whose sum is σ = 11631632. Its totient is φ = 5815812.

The previous prime is 8723707. The next prime is 8723731. The reversal of 8723721 is 1273278.

8723721 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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.

It is not a de Polignac number, because 8723721 - 2⁷ = 8723593 is a prime.

It is a super-2 number, since 2×8723721² = 152206616171682, which contains 22 as substring.

It is a Duffinian number.

8723721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (8723731) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1453951 + ... + 1453956.

It is an arithmetic number, because the mean of its divisors is an integer number (2907908).

Almost surely, 2^8723721 is an apocalyptic number.

It is an amenable number.

8723721 is a deficient number, since it is larger than the sum of its proper divisors (2907911).

8723721 is a wasteful number, since it uses less digits than its factorization.

8723721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2907910.

The product of its digits is 4704, while the sum is 30.

The square root of 8723721 is about 2953.5945896483. The cubic root of 8723721 is about 205.8577662084.

Adding to 8723721 its reverse (1273278), we get a palindrome (9996999).

The spelling of 8723721 in words is "eight million, seven hundred twenty-three thousand, seven hundred twenty-one".