644349847 has 2 divisors, whose sum is σ = 644349848. Its totient is φ = 644349846.

The previous prime is 644349841. The next prime is 644349851. The reversal of 644349847 is 748943446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644349847 - 2¹¹ = 644347799 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644349847.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644349841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322174923 + 322174924.

It is an arithmetic number, because the mean of its divisors is an integer number (322174924).

Almost surely, 2^644349847 is an apocalyptic number.

644349847 is a deficient number, since it is larger than the sum of its proper divisors (1).

644349847 is an equidigital number, since it uses as much as digits as its factorization.

644349847 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2322432, while the sum is 49.

The square root of 644349847 is about 25384.0470965526. The cubic root of 644349847 is about 863.7218571814.

The spelling of 644349847 in words is "six hundred forty-four million, three hundred forty-nine thousand, eight hundred forty-seven".