6457915721 has 4 divisors (see below), whose sum is σ = 6680602500. Its totient is φ = 6235228944.

The previous prime is 6457915703. The next prime is 6457915769. The reversal of 6457915721 is 1275197546.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1293481225 + 5164434496 = 35965^2 + 71864^2 .

It is a cyclic number.

It is not a de Polignac number, because 6457915721 - 2¹⁴ = 6457899337 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6457915021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111343346 + ... + 111343403.

It is an arithmetic number, because the mean of its divisors is an integer number (1670150625).

Almost surely, 2^6457915721 is an apocalyptic number.

It is an amenable number.

6457915721 is a deficient number, since it is larger than the sum of its proper divisors (222686779).

6457915721 is a wasteful number, since it uses less digits than its factorization.

6457915721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222686778.

The product of its digits is 529200, while the sum is 47.

The square root of 6457915721 is about 80361.1580367033. The cubic root of 6457915721 is about 1862.2191612110.

The spelling of 6457915721 in words is "six billion, four hundred fifty-seven million, nine hundred fifteen thousand, seven hundred twenty-one".