8457721 has 16 divisors (see below), whose sum is σ = 9483264. Its totient is φ = 7501824.

The previous prime is 8457677. The next prime is 8457727. The reversal of 8457721 is 1277548.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 8457721 - 2⁷ = 8457593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8457727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37816 + ... + 38038.

It is an arithmetic number, because the mean of its divisors is an integer number (592704).

Almost surely, 2^8457721 is an apocalyptic number.

It is an amenable number.

8457721 is a deficient number, since it is larger than the sum of its proper divisors (1025543).

8457721 is a wasteful number, since it uses less digits than its factorization.

8457721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360.

The product of its digits is 15680, while the sum is 34.

The square root of 8457721 is about 2908.2161198921. The cubic root of 8457721 is about 203.7438233163.

The spelling of 8457721 in words is "eight million, four hundred fifty-seven thousand, seven hundred twenty-one".