644367 has 4 divisors (see below), whose sum is σ = 859160. Its totient is φ = 429576.

The previous prime is 644363. The next prime is 644377. The reversal of 644367 is 763446.

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

It is not a de Polignac number, because 644367 - 2² = 644363 is a prime.

It is a D-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 (644363) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 107392 + ... + 107397.

It is an arithmetic number, because the mean of its divisors is an integer number (214790).

2⁶⁴⁴³⁶⁷ is an apocalyptic number.

644367 is a deficient number, since it is larger than the sum of its proper divisors (214793).

644367 is a wasteful number, since it uses less digits than its factorization.

644367 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214792.

The product of its digits is 12096, while the sum is 30.

The square root of 644367 is about 802.7247348874. The cubic root of 644367 is about 86.3729521387.

The spelling of 644367 in words is "six hundred forty-four thousand, three hundred sixty-seven".