6640945920 has 576 divisors, whose sum is σ = 27306531840. Its totient is φ = 1496973312.

The previous prime is 6640945919. The next prime is 6640945933. The reversal of 6640945920 is 295490466.

It is a tau number, because it is divible by the number of its divisors (576).

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 63 ways as a sum of consecutive naturals, for example, 23466099 + ... + 23466381.

Almost surely, 2^6640945920 is an apocalyptic number.

6640945920 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 6640945920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13653265920).

6640945920 is an abundant number, since it is smaller than the sum of its proper divisors (20665585920).

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

6640945920 is a wasteful number, since it uses less digits than its factorization.

6640945920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417 (or 397 counting only the distinct ones).

The product of its (nonzero) digits is 466560, while the sum is 45.

The square root of 6640945920 is about 81491.9991164777. Note that the first 3 decimals coincide. The cubic root of 6640945920 is about 1879.6485233987.

The spelling of 6640945920 in words is "six billion, six hundred forty million, nine hundred forty-five thousand, nine hundred twenty".