640477440 has 216 divisors, whose sum is σ = 2259948600. Its totient is φ = 167411712.

The previous prime is 640477429. The next prime is 640477447. The reversal of 640477440 is 44774046.

640477440 is a `hidden beast` number, since 640 + 4 + 7 + 7 + 4 + 4 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 249387264 + 391090176 = 15792^2 + 19776^2 .

It is a super-2 number, since 2×640477440² = 820422702297907200, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 640477395 and 640477404.

It is not an unprimeable number, because it can be changed into a prime (640477447) 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 23 ways as a sum of consecutive naturals, for example, 610036 + ... + 611084.

It is an arithmetic number, because the mean of its divisors is an integer number (10462725).

Almost surely, 2^640477440 is an apocalyptic number.

640477440 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 640477440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1129974300).

640477440 is an abundant number, since it is smaller than the sum of its proper divisors (1619471160).

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

640477440 is a wasteful number, since it uses less digits than its factorization.

640477440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1129 (or 1112 counting only the distinct ones).

The product of its (nonzero) digits is 75264, while the sum is 36.

The square root of 640477440 is about 25307.6557586830. The cubic root of 640477440 is about 861.9881171841.

The spelling of 640477440 in words is "six hundred forty million, four hundred seventy-seven thousand, four hundred forty".