640481280 has 96 divisors (see below), whose sum is σ = 2049138000. Its totient is φ = 170786816.

The previous prime is 640481251. The next prime is 640481287. The reversal of 640481280 is 82184046.

It is a tau number, because it is divible by the number of its divisors (96).

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640481287) 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 7 ways as a sum of consecutive naturals, for example, 20296 + ... + 41144.

Almost surely, 2^640481280 is an apocalyptic number.

640481280 is a gapful number since it is divisible by the number (60) 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 640481280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1024569000).

640481280 is an abundant number, since it is smaller than the sum of its proper divisors (1408656720).

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

640481280 is a wasteful number, since it uses less digits than its factorization.

640481280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20879 (or 20859 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 33.

The square root of 640481280 is about 25307.7316249402. The cubic root of 640481280 is about 861.9898398718.

The spelling of 640481280 in words is "six hundred forty million, four hundred eighty-one thousand, two hundred eighty".