644563 has 2 divisors, whose sum is σ = 644564. Its totient is φ = 644562.

The previous prime is 644557. The next prime is 644569. The reversal of 644563 is 365446.

It is a balanced prime because it is at equal distance from previous prime (644557) and next prime (644569).

It is a cyclic number.

It is not a de Polignac number, because 644563 - 2⁵ = 644531 is a prime.

It is a super-2 number, since 2×644563² = 830922921938, which contains 22 as substring.

644563 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (644569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322281 + 322282.

It is an arithmetic number, because the mean of its divisors is an integer number (322282).

2⁶⁴⁴⁵⁶³ is an apocalyptic number.

644563 is a deficient number, since it is larger than the sum of its proper divisors (1).

644563 is an equidigital number, since it uses as much as digits as its factorization.

644563 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 28.

The square root of 644563 is about 802.8468097962. The cubic root of 644563 is about 86.3817087337.

The spelling of 644563 in words is "six hundred forty-four thousand, five hundred sixty-three".