644651200 has 168 divisors, whose sum is σ = 1682642304. Its totient is φ = 242688000.

The previous prime is 644651197. The next prime is 644651207. The reversal of 644651200 is 2156446.

It is a super-2 number, since 2×644651200² = 831150339322880000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644651207) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2033442 + ... + 2033758.

It is an arithmetic number, because the mean of its divisors is an integer number (10015728).

Almost surely, 2^644651200 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644651200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (841321152).

644651200 is an abundant number, since it is smaller than the sum of its proper divisors (1037991104).

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

644651200 is a wasteful number, since it uses less digits than its factorization.

644651200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411 (or 396 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 644651200 is about 25389.9822764806. The cubic root of 644651200 is about 863.8564862226.

The spelling of 644651200 in words is "six hundred forty-four million, six hundred fifty-one thousand, two hundred".