644024749 has 2 divisors, whose sum is σ = 644024750. Its totient is φ = 644024748.

The previous prime is 644024729. The next prime is 644024789. The reversal of 644024749 is 947420446.

It is an a-pointer prime, because the next prime (644024789) can be obtained adding 644024749 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 640849225 + 3175524 = 25315^2 + 1782^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644024749 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644024729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322012374 + 322012375.

It is an arithmetic number, because the mean of its divisors is an integer number (322012375).

Almost surely, 2^644024749 is an apocalyptic number.

It is an amenable number.

644024749 is a deficient number, since it is larger than the sum of its proper divisors (1).

644024749 is an equidigital number, since it uses as much as digits as its factorization.

644024749 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 193536, while the sum is 40.

The square root of 644024749 is about 25377.6426998254. The cubic root of 644024749 is about 863.5765730181.

The spelling of 644024749 in words is "six hundred forty-four million, twenty-four thousand, seven hundred forty-nine".