644306233 has 2 divisors, whose sum is σ = 644306234. Its totient is φ = 644306232.

The previous prime is 644306231. The next prime is 644306251. The reversal of 644306233 is 332603446.

644306233 is nontrivially palindromic in base 3.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 601377529 + 42928704 = 24523^2 + 6552^2 .

It is a cyclic number.

It is not a de Polignac number, because 644306233 - 2¹ = 644306231 is a prime.

Together with 644306231, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 644306195 and 644306204.

It is not a weakly prime, because it can be changed into another prime (644306231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322153116 + 322153117.

It is an arithmetic number, because the mean of its divisors is an integer number (322153117).

Almost surely, 2^644306233 is an apocalyptic number.

It is an amenable number.

644306233 is a deficient number, since it is larger than the sum of its proper divisors (1).

644306233 is an equidigital number, since it uses as much as digits as its factorization.

644306233 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 31104, while the sum is 31.

The square root of 644306233 is about 25383.1879991462. The cubic root of 644306233 is about 863.7023692096.

Adding to 644306233 its reverse (332603446), we get a palindrome (976909679).

The spelling of 644306233 in words is "six hundred forty-four million, three hundred six thousand, two hundred thirty-three".