644999144 has 16 divisors (see below), whose sum is σ = 1248385920. Its totient is φ = 312096240.

The previous prime is 644999101. The next prime is 644999149. The reversal of 644999144 is 441999446.

It is a super-3 number, since 3×644999144³ (a number of 27 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644999092 and 644999101.

It is not an unprimeable number, because it can be changed into a prime (644999149) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1300154 + ... + 1300649.

It is an arithmetic number, because the mean of its divisors is an integer number (78024120).

Almost surely, 2^644999144 is an apocalyptic number.

It is an amenable number.

644999144 is a deficient number, since it is larger than the sum of its proper divisors (603386776).

644999144 is a wasteful number, since it uses less digits than its factorization.

644999144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2600840 (or 2600836 counting only the distinct ones).

The product of its digits is 1119744, while the sum is 50.

The square root of 644999144 is about 25396.8333459115. The cubic root of 644999144 is about 864.0118775516.

The spelling of 644999144 in words is "six hundred forty-four million, nine hundred ninety-nine thousand, one hundred forty-four".