6640044660 has 60 divisors (see below), whose sum is σ = 20830071108. Its totient is φ = 1770678144.

The previous prime is 6640044643. The next prime is 6640044661. The reversal of 6640044660 is 664400466.

It is a happy number.

6640044660 is a `hidden beast` number, since 6 + 640 + 0 + 4 + 4 + 6 + 6 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 3192476004 + 3447568656 = 56502^2 + 58716^2 .

It is a tau number, because it is divible by the number of its divisors (60).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640044661) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2047777 + ... + 2051016.

Almost surely, 2^6640044660 is an apocalyptic number.

6640044660 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

6640044660 is an abundant number, since it is smaller than the sum of its proper divisors (14190026448).

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

6640044660 is a wasteful number, since it uses less digits than its factorization.

6640044660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4098814 (or 4098803 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The square root of 6640044660 is about 81486.4691835399. The cubic root of 6640044660 is about 1879.5634888927.

The spelling of 6640044660 in words is "six billion, six hundred forty million, forty-four thousand, six hundred sixty".