644420347 has 2 divisors, whose sum is σ = 644420348. Its totient is φ = 644420346.

The previous prime is 644420327. The next prime is 644420351. The reversal of 644420347 is 743024446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644420347 - 2¹⁹ = 643896059 is a prime.

It is not a weakly prime, because it can be changed into another prime (644420327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322210173 + 322210174.

It is an arithmetic number, because the mean of its divisors is an integer number (322210174).

Almost surely, 2^644420347 is an apocalyptic number.

644420347 is a deficient number, since it is larger than the sum of its proper divisors (1).

644420347 is an equidigital number, since it uses as much as digits as its factorization.

644420347 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64512, while the sum is 34.

The square root of 644420347 is about 25385.4357260221. The cubic root of 644420347 is about 863.7533567209.

The spelling of 644420347 in words is "six hundred forty-four million, four hundred twenty thousand, three hundred forty-seven".