8724721 has 2 divisors, whose sum is σ = 8724722. Its totient is φ = 8724720.

The previous prime is 8724719. The next prime is 8724739. The reversal of 8724721 is 1274278.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8410000 + 314721 = 2900^2 + 561^2 .

It is a cyclic number.

It is not a de Polignac number, because 8724721 - 2¹ = 8724719 is a prime.

It is a super-2 number, since 2×8724721² = 152241513055682, which contains 22 as substring.

Together with 8724719, it forms a pair of twin primes.

It is equal to p₅₈₅₂₈₃ and since 8724721 and 585283 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (8724421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4362360 + 4362361.

It is an arithmetic number, because the mean of its divisors is an integer number (4362361).

Almost surely, 2^8724721 is an apocalyptic number.

It is an amenable number.

8724721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8724721 is an equidigital number, since it uses as much as digits as its factorization.

8724721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6272, while the sum is 31.

The square root of 8724721 is about 2953.7638700478. The cubic root of 8724721 is about 205.8656317320.

Adding to 8724721 its reverse (1274278), we get a palindrome (9998999).

The spelling of 8724721 in words is "eight million, seven hundred twenty-four thousand, seven hundred twenty-one".