640007744 has 14 divisors (see below), whose sum is σ = 1270015494. Its totient is φ = 320003840.

The previous prime is 640007713. The next prime is 640007777. The reversal of 640007744 is 447700046.

It can be written as a sum of positive squares in only one way, i.e., 538240000 + 101767744 = 23200^2 + 10088^2 .

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a self number, because there is not a number n which added to its sum of digits gives 640007744.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4999997 + ... + 5000124.

Almost surely, 2^640007744 is an apocalyptic number.

640007744 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

640007744 is a deficient number, since it is larger than the sum of its proper divisors (630007750).

640007744 is a wasteful number, since it uses less digits than its factorization.

640007744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10000133 (or 10000123 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 32.

The square root of 640007744 is about 25298.3743351228. The cubic root of 640007744 is about 861.7773518200. Note that the first 3 decimals are identical.

The spelling of 640007744 in words is "six hundred forty million, seven thousand, seven hundred forty-four".