6439977640 has 32 divisors (see below), whose sum is σ = 14495902560. Its totient is φ = 2574932800.

The previous prime is 6439977619. The next prime is 6439977671. The reversal of 6439977640 is 467799346.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69435 + ... + 133045.

It is an arithmetic number, because the mean of its divisors is an integer number (452996955).

Almost surely, 2^6439977640 is an apocalyptic number.

It is an amenable number.

6439977640 is an abundant number, since it is smaller than the sum of its proper divisors (8055924920).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6439977640 is a wasteful number, since it uses less digits than its factorization.

6439977640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66153 (or 66149 counting only the distinct ones).

The product of its (nonzero) digits is 6858432, while the sum is 55.

The square root of 6439977640 is about 80249.4712755168. The cubic root of 6439977640 is about 1860.4933404433.

The spelling of 6439977640 in words is "six billion, four hundred thirty-nine million, nine hundred seventy-seven thousand, six hundred forty".