1644650660 has 24 divisors (see below), whose sum is σ = 3455455416. Its totient is φ = 657538560.

The previous prime is 1644650647. The next prime is 1644650699. The reversal of 1644650660 is 660564461.

It can be written as a sum of positive squares in 4 ways, for example, as 187854436 + 1456796224 = 13706^2 + 38168^2 .

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

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 7 ways as a sum of consecutive naturals, for example, 24194 + ... + 62246.

It is an arithmetic number, because the mean of its divisors is an integer number (143977309).

Almost surely, 2^1644650660 is an apocalyptic number.

1644650660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1644650660 is an abundant number, since it is smaller than the sum of its proper divisors (1810804756).

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

1644650660 is a wasteful number, since it uses less digits than its factorization.

1644650660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40223 (or 40221 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 38.

The square root of 1644650660 is about 40554.2927444186. The cubic root of 1644650660 is about 1180.3873716224.

The spelling of 1644650660 in words is "one billion, six hundred forty-four million, six hundred fifty thousand, six hundred sixty".