644073 has 4 divisors (see below), whose sum is σ = 858768. Its totient is φ = 429380.

The previous prime is 644057. The next prime is 644089. The reversal of 644073 is 370446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (644057) and next prime (644089).

It is a cyclic number.

It is not a de Polignac number, because 644073 - 2⁴ = 644057 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (644053) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107343 + ... + 107348.

It is an arithmetic number, because the mean of its divisors is an integer number (214692).

2⁶⁴⁴⁰⁷³ is an apocalyptic number.

It is an amenable number.

644073 is a deficient number, since it is larger than the sum of its proper divisors (214695).

644073 is a wasteful number, since it uses less digits than its factorization.

644073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214694.

The product of its (nonzero) digits is 2016, while the sum is 24.

The square root of 644073 is about 802.5415877075. The cubic root of 644073 is about 86.3598139163.

The spelling of 644073 in words is "six hundred forty-four thousand, seventy-three".