644022433 has 2 divisors, whose sum is σ = 644022434. Its totient is φ = 644022432.

The previous prime is 644022419. The next prime is 644022473. The reversal of 644022433 is 334220446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 398880784 + 245141649 = 19972^2 + 15657^2 .

It is a cyclic number.

It is not a de Polignac number, because 644022433 - 2²⁹ = 107151521 is a prime.

It is not a weakly prime, because it can be changed into another prime (644022403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322011216 + 322011217.

It is an arithmetic number, because the mean of its divisors is an integer number (322011217).

Almost surely, 2^644022433 is an apocalyptic number.

It is an amenable number.

644022433 is a deficient number, since it is larger than the sum of its proper divisors (1).

644022433 is an equidigital number, since it uses as much as digits as its factorization.

644022433 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13824, while the sum is 28.

The square root of 644022433 is about 25377.5970690686. The cubic root of 644022433 is about 863.5755378375.

Adding to 644022433 its reverse (334220446), we get a palindrome (978242879).

The spelling of 644022433 in words is "six hundred forty-four million, twenty-two thousand, four hundred thirty-three".