640283904 has 108 divisors (see below), whose sum is σ = 1988196756. Its totient is φ = 197001216.

The previous prime is 640283881. The next prime is 640283909. The reversal of 640283904 is 409382046.

It is a happy number.

640283904 is a `hidden beast` number, since 640 + 2 + 8 + 3 + 9 + 0 + 4 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 66585600 + 573698304 = 8160^2 + 23952^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640283909) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19264 + ... + 40640.

Almost surely, 2^640283904 is an apocalyptic number.

640283904 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640283904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (994098378).

640283904 is an abundant number, since it is smaller than the sum of its proper divisors (1347912852).

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

640283904 is a wasteful number, since it uses less digits than its factorization.

640283904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21412 (or 21395 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 640283904 is about 25303.8318046892. The cubic root of 640283904 is about 861.9012848056.

The spelling of 640283904 in words is "six hundred forty million, two hundred eighty-three thousand, nine hundred four".