1644664900 has 72 divisors (see below), whose sum is σ = 3621705696. Its totient is φ = 648211200.

The previous prime is 1644664891. The next prime is 1644664913. The reversal of 1644664900 is 94664461.

It is an unprimeable number.

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, 3006427 + ... + 3006973.

It is an arithmetic number, because the mean of its divisors is an integer number (50301468).

Almost surely, 2^1644664900 is an apocalyptic number.

1644664900 is a gapful number since it is divisible by the number (10) 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 1644664900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1810852848).

1644664900 is an abundant number, since it is smaller than the sum of its proper divisors (1977040796).

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

1644664900 is a wasteful number, since it uses less digits than its factorization.

1644664900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 949 (or 942 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 40.

The square root of 1644664900 is about 40554.4683111491. The cubic root of 1644664900 is about 1180.3907783575.

The spelling of 1644664900 in words is "one billion, six hundred forty-four million, six hundred sixty-four thousand, nine hundred".