644742000 has 720 divisors, whose sum is σ = 2838112992. Its totient is φ = 135475200.

The previous prime is 644741969. The next prime is 644742011. The reversal of 644742000 is 247446.

It is a tau number, because it is divible by the number of its divisors (720).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 14993979 + ... + 14994021.

Almost surely, 2^644742000 is an apocalyptic number.

644742000 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644742000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1419056496).

644742000 is an abundant number, since it is smaller than the sum of its proper divisors (2193370992).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644742000 is a wasteful number, since it uses less digits than its factorization.

644742000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103 (or 77 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 27.

The square root of 644742000 is about 25391.7703203223. The cubic root of 644742000 is about 863.8970427729.

Adding to 644742000 its reverse (247446), we get a palindrome (644989446).

The spelling of 644742000 in words is "six hundred forty-four million, seven hundred forty-two thousand".