7257721 has 2 divisors, whose sum is σ = 7257722. Its totient is φ = 7257720.

The previous prime is 7257709. The next prime is 7257739. The reversal of 7257721 is 1277527.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6125625 + 1132096 = 2475^2 + 1064^2 .

It is a cyclic number.

It is not a de Polignac number, because 7257721 - 2¹⁷ = 7126649 is a prime.

It is a super-2 number, since 2×7257721² = 105349028227682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (7257781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3628860 + 3628861.

It is an arithmetic number, because the mean of its divisors is an integer number (3628861).

Almost surely, 2^7257721 is an apocalyptic number.

It is an amenable number.

7257721 is a deficient number, since it is larger than the sum of its proper divisors (1).

7257721 is an equidigital number, since it uses as much as digits as its factorization.

7257721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6860, while the sum is 31.

The square root of 7257721 is about 2694.0157757519. The cubic root of 7257721 is about 193.6125134918.

The spelling of 7257721 in words is "seven million, two hundred fifty-seven thousand, seven hundred twenty-one".