644420425 has 24 divisors (see below), whose sum is σ = 873908352. Its totient is φ = 467496000.

The previous prime is 644420423. The next prime is 644420443. The reversal of 644420425 is 524024446.

It is a happy number.

It is not a de Polignac number, because 644420425 - 2¹ = 644420423 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644420423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 115807 + ... + 121243.

It is an arithmetic number, because the mean of its divisors is an integer number (36412848).

Almost surely, 2^644420425 is an apocalyptic number.

It is an amenable number.

644420425 is a deficient number, since it is larger than the sum of its proper divisors (229487927).

644420425 is a wasteful number, since it uses less digits than its factorization.

644420425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5889 (or 5884 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 31.

The square root of 644420425 is about 25385.4372623361. The cubic root of 644420425 is about 863.7533915702.

The spelling of 644420425 in words is "six hundred forty-four million, four hundred twenty thousand, four hundred twenty-five".