644846400 has 672 divisors, whose sum is σ = 2721254400. Its totient is φ = 146995200.

The previous prime is 644846399. The next prime is 644846441. The reversal of 644846400 is 4648446.

644846400 is a `hidden beast` number, since 6 + 4 + 4 + 8 + 4 + 640 + 0 = 666.

It is a super-3 number, since 3×644846400³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 10929571 + ... + 10929629.

Almost surely, 2^644846400 is an apocalyptic number.

644846400 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 644846400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1360627200).

644846400 is an abundant number, since it is smaller than the sum of its proper divisors (2076408000).

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

644846400 is a wasteful number, since it uses less digits than its factorization.

644846400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124 (or 103 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 36.

The square root of 644846400 is about 25393.8260212990. The cubic root of 644846400 is about 863.9436691669.

The spelling of 644846400 in words is "six hundred forty-four million, eight hundred forty-six thousand, four hundred".