644085 has 32 divisors (see below), whose sum is σ = 1236480. Its totient is φ = 316224.

The previous prime is 644057. The next prime is 644089. The reversal of 644085 is 580446.

644085 is nontrivially palindromic in base 14.

It is not a de Polignac number, because 644085 - 2⁵ = 644053 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644089) 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 31 ways as a sum of consecutive naturals, for example, 1572 + ... + 1938.

It is an arithmetic number, because the mean of its divisors is an integer number (38640).

2⁶⁴⁴⁰⁸⁵ is an apocalyptic number.

644085 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

644085 is a deficient number, since it is larger than the sum of its proper divisors (592395).

644085 is a wasteful number, since it uses less digits than its factorization.

644085 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394 (or 388 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 644085 is about 802.5490639207. The cubic root of 644085 is about 86.3603502485.

The spelling of 644085 in words is "six hundred forty-four thousand, eighty-five".