6399945523 has 4 divisors (see below), whose sum is σ = 6678204048. Its totient is φ = 6121687000.

The previous prime is 6399945521. The next prime is 6399945529. The reversal of 6399945523 is 3255499936.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 6399945523 - 2¹ = 6399945521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6399945521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139129228 + ... + 139129273.

It is an arithmetic number, because the mean of its divisors is an integer number (1669551012).

Almost surely, 2^6399945523 is an apocalyptic number.

6399945523 is a deficient number, since it is larger than the sum of its proper divisors (278258525).

6399945523 is a wasteful number, since it uses less digits than its factorization.

6399945523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278258524.

The product of its digits is 7873200, while the sum is 55.

The square root of 6399945523 is about 79999.6595180255. The cubic root of 6399945523 is about 1856.6302655169.

The spelling of 6399945523 in words is "six billion, three hundred ninety-nine million, nine hundred forty-five thousand, five hundred twenty-three".