7824721 has 2 divisors, whose sum is σ = 7824722. Its totient is φ = 7824720.

The previous prime is 7824703. The next prime is 7824731. The reversal of 7824721 is 1274287.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5934096 + 1890625 = 2436^2 + 1375^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7824721 is a prime.

It is a super-2 number, since 2×7824721² = 122452517455682, which contains 22 as substring.

It is a nialpdrome in base 16.

It is not a weakly prime, because it can be changed into another prime (7824731) 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 as a sum of consecutive naturals, namely, 3912360 + 3912361.

It is an arithmetic number, because the mean of its divisors is an integer number (3912361).

Almost surely, 2^7824721 is an apocalyptic number.

It is an amenable number.

7824721 is a deficient number, since it is larger than the sum of its proper divisors (1).

7824721 is an equidigital number, since it uses as much as digits as its factorization.

7824721 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 7824721 is about 2797.2702765375. The cubic root of 7824721 is about 198.5285422774.

The spelling of 7824721 in words is "seven million, eight hundred twenty-four thousand, seven hundred twenty-one".