6393490721 has 4 divisors (see below), whose sum is σ = 6393742212. Its totient is φ = 6393239232.

The previous prime is 6393490717. The next prime is 6393490723. The reversal of 6393490721 is 1270943936.

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 4081804321 + 2311686400 = 63889^2 + 48080^2 .

It is a cyclic number.

It is not a de Polignac number, because 6393490721 - 2² = 6393490717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6393490723) 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, 82700 + ... + 140093.

It is an arithmetic number, because the mean of its divisors is an integer number (1598435553).

Almost surely, 2^6393490721 is an apocalyptic number.

It is an amenable number.

6393490721 is a deficient number, since it is larger than the sum of its proper divisors (251491).

6393490721 is a wasteful number, since it uses less digits than its factorization.

6393490721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251490.

The product of its (nonzero) digits is 244944, while the sum is 44.

The square root of 6393490721 is about 79959.3066565738. The cubic root of 6393490721 is about 1856.0058741616.

The spelling of 6393490721 in words is "six billion, three hundred ninety-three million, four hundred ninety thousand, seven hundred twenty-one".