6640620100 has 81 divisors (see below), whose sum is σ = 14977481701. Its totient is φ = 2555526400.

The previous prime is 6640620079. The next prime is 6640620139. The reversal of 6640620100 is 10260466.

It is a happy number.

The square root of 6640620100 is 81490.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 13 ways, for example, as 2908876356 + 3731743744 = 53934^2 + 61088^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 23631960 + ... + 23632240.

Almost surely, 2^6640620100 is an apocalyptic number.

6640620100 is the 81490-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6640620100

6640620100 is an abundant number, since it is smaller than the sum of its proper divisors (8336861601).

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

6640620100 is a wasteful number, since it uses less digits than its factorization.

6640620100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 634 (or 317 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The cubic root of 6640620100 is about 1879.6177829437.

Multiplying 6640620100 by its sum of digits (25), we get a square (166015502500 = 407450²).

6640620100 divided by its sum of digits (25) gives a square (265624804 = 16298²).

Adding to 6640620100 its reverse (10260466), we get a palindrome (6650880566).

The spelling of 6640620100 in words is "six billion, six hundred forty million, six hundred twenty thousand, one hundred".