644569 has 2 divisors, whose sum is σ = 644570. Its totient is φ = 644568.

The previous prime is 644563. The next prime is 644593. The reversal of 644569 is 965446.

644569 is nontrivially palindromic in base 16.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 632025 + 12544 = 795^2 + 112^2 .

It is a cyclic number.

It is not a de Polignac number, because 644569 - 2⁹ = 644057 is a prime.

It is a super-2 number, since 2×644569² = 830938391522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (644563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322284 + 322285.

It is an arithmetic number, because the mean of its divisors is an integer number (322285).

2⁶⁴⁴⁵⁶⁹ is an apocalyptic number.

It is an amenable number.

644569 is a deficient number, since it is larger than the sum of its proper divisors (1).

644569 is an equidigital number, since it uses as much as digits as its factorization.

644569 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 34.

The square root of 644569 is about 802.8505464904. The cubic root of 644569 is about 86.3819767647.

The spelling of 644569 in words is "six hundred forty-four thousand, five hundred sixty-nine".