6400640016 has 135 divisors (see below), whose sum is σ = 18384337309. Its totient is φ = 2078823936.

The previous prime is 6400639943. The next prime is 6400640017. The reversal of 6400640016 is 6100460046.

The square root of 6400640016 is 80004.

It is a perfect power (a square), and thus also a powerful number.

6400640016 is a `hidden beast` number, since 6 + 4 + 0 + 0 + 640 + 0 + 16 = 666.

It can be written as a sum of positive squares in only one way, i.e., 112784400 + 6287855616 = 10620^2 + 79296^2 .

It is a super-2 number, since 2×6400640016² = 81936385228840960512, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6400640017) 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 26 ways as a sum of consecutive naturals, for example, 56642776 + ... + 56642888.

Almost surely, 2^6400640016 is an apocalyptic number.

6400640016 is the 80004-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6400640016

6400640016 is an abundant number, since it is smaller than the sum of its proper divisors (11983697293).

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

6400640016 is a wasteful number, since it uses less digits than its factorization.

6400640016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 358 (or 177 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The cubic root of 6400640016 is about 1856.6974207805.

It can be divided in two parts, 6400 and 640016, that added together give a square (646416 = 804²).

The spelling of 6400640016 in words is "six billion, four hundred million, six hundred forty thousand, sixteen".