1644705085 has 4 divisors (see below), whose sum is σ = 1973646108. Its totient is φ = 1315764064.

The previous prime is 1644705077. The next prime is 1644705089. The reversal of 1644705085 is 5805074461.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 706018041 + 938687044 = 26571^2 + 30638^2 .

It is a cyclic number.

It is not a de Polignac number, because 1644705085 - 2³ = 1644705077 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1644705089) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164470504 + ... + 164470513.

It is an arithmetic number, because the mean of its divisors is an integer number (493411527).

Almost surely, 2^1644705085 is an apocalyptic number.

It is an amenable number.

1644705085 is a deficient number, since it is larger than the sum of its proper divisors (328941023).

1644705085 is an equidigital number, since it uses as much as digits as its factorization.

1644705085 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328941022.

The product of its (nonzero) digits is 134400, while the sum is 40.

The square root of 1644705085 is about 40554.9637529119. The cubic root of 1644705085 is about 1180.4003919911.

The spelling of 1644705085 in words is "one billion, six hundred forty-four million, seven hundred five thousand, eighty-five".