644236847 has 2 divisors, whose sum is σ = 644236848. Its totient is φ = 644236846.

The previous prime is 644236841. The next prime is 644236861. The reversal of 644236847 is 748632446.

644236847 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644236847 is a prime.

It is a super-2 number, since 2×644236847² = 830082230065002818, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644236798 and 644236807.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644236841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322118423 + 322118424.

It is an arithmetic number, because the mean of its divisors is an integer number (322118424).

Almost surely, 2^644236847 is an apocalyptic number.

644236847 is a deficient number, since it is larger than the sum of its proper divisors (1).

644236847 is an equidigital number, since it uses as much as digits as its factorization.

644236847 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 774144, while the sum is 44.

The square root of 644236847 is about 25381.8211915536. The cubic root of 644236847 is about 863.6713637648.

The spelling of 644236847 in words is "six hundred forty-four million, two hundred thirty-six thousand, eight hundred forty-seven".