6885440640 has 640 divisors, whose sum is σ = 28084961520. Its totient is φ = 1592524800.

The previous prime is 6885440629. The next prime is 6885440651. The reversal of 6885440640 is 460445886.

6885440640 is a `hidden beast` number, since 68 + 8 + 544 + 0 + 6 + 40 = 666.

It is an interprime number because it is at equal distance from previous prime (6885440629) and next prime (6885440651).

It can be written as a sum of positive squares in 8 ways, for example, as 3914754624 + 2970686016 = 62568^2 + 54504^2 .

It is a tau number, because it is divible by the number of its divisors (640).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 11456340 + ... + 11456940.

Almost surely, 2^6885440640 is an apocalyptic number.

6885440640 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 6885440640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14042480760).

6885440640 is an abundant number, since it is smaller than the sum of its proper divisors (21199520880).

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

6885440640 is a wasteful number, since it uses less digits than its factorization.

6885440640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 662 (or 641 counting only the distinct ones).

The product of its (nonzero) digits is 737280, while the sum is 45.

The square root of 6885440640 is about 82978.5553019574. Note that the first 3 decimals coincide. The cubic root of 6885440640 is about 1902.4382952342.

It can be divided in two parts, 6885 and 440640, that multiplied together give a square (3033806400 = 55080²).

The spelling of 6885440640 in words is "six billion, eight hundred eighty-five million, four hundred forty thousand, six hundred forty".