7158721 has 2 divisors, whose sum is σ = 7158722. Its totient is φ = 7158720.

The previous prime is 7158719. The next prime is 7158733. The reversal of 7158721 is 1278517.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5948721 + 1210000 = 2439^2 + 1100^2 .

It is a cyclic number.

It is not a de Polignac number, because 7158721 - 2¹ = 7158719 is a prime.

Together with 7158719, it forms a pair of twin primes.

It is equal to p₄₈₆₇₂₄ and since 7158721 and 486724 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 (7158761) 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, 3579360 + 3579361.

It is an arithmetic number, because the mean of its divisors is an integer number (3579361).

Almost surely, 2^7158721 is an apocalyptic number.

It is an amenable number.

7158721 is a deficient number, since it is larger than the sum of its proper divisors (1).

7158721 is an equidigital number, since it uses as much as digits as its factorization.

7158721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3920, while the sum is 31.

The square root of 7158721 is about 2675.5786290072. The cubic root of 7158721 is about 192.7281468819.

The spelling of 7158721 in words is "seven million, one hundred fifty-eight thousand, seven hundred twenty-one".