644732447 has 2 divisors, whose sum is σ = 644732448. Its totient is φ = 644732446.

The previous prime is 644732441. The next prime is 644732477. The reversal of 644732447 is 744237446.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644732447 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 (644732441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322366223 + 322366224.

It is an arithmetic number, because the mean of its divisors is an integer number (322366224).

Almost surely, 2^644732447 is an apocalyptic number.

644732447 is a deficient number, since it is larger than the sum of its proper divisors (1).

644732447 is an equidigital number, since it uses as much as digits as its factorization.

644732447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 451584, while the sum is 41.

The square root of 644732447 is about 25391.5822074955. The cubic root of 644732447 is about 863.8927760279.

The spelling of 644732447 in words is "six hundred forty-four million, seven hundred thirty-two thousand, four hundred forty-seven".