640000000 has 112 divisors (see below), whose sum is σ = 1599898248. Its totient is φ = 256000000.

The previous prime is 639999967. The next prime is 640000019. The reversal of 640000000 is 46.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 4 ways, for example, as 386043904 + 253956096 = 19648^2 + 15936^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a nialpdrome in base 10.

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, 127999998 + ... + 128000002.

Almost surely, 2^640000000 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (799949124).

640000000 is an abundant number, since it is smaller than the sum of its proper divisors (959898248).

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

640000000 is an frugal number, since it uses more digits than its factorization.

640000000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61 (or 7 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 10.

The square root of 640000000 is about 25298.2212813470. The cubic root of 640000000 is about 861.7738760128.

Multiplying 640000000 by its sum of digits (10), we get a square (6400000000 = 80000²).

640000000 divided by its sum of digits (10) gives a 6-th power (64000000 = 20⁶).

Adding to 640000000 its reverse (46), we get a palindrome (640000046).

The spelling of 640000000 in words is "six hundred forty million", and thus it is an aban number.