645620400 has 270 divisors, whose sum is σ = 2320249932. Its totient is φ = 166233600.

The previous prime is 645620351. The next prime is 645620411. The reversal of 645620400 is 4026546.

It is a happy number.

645620400 is a `hidden beast` number, since 6 + 456 + 204 + 0 + 0 = 666.

645620400 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-3 number, since 3×645620400³ (a number of 27 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 4928335 + ... + 4928465.

Almost surely, 2^645620400 is an apocalyptic number.

645620400 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 645620400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1160124966).

645620400 is an abundant number, since it is smaller than the sum of its proper divisors (1674629532).

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

645620400 is a wasteful number, since it uses less digits than its factorization.

645620400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229 (or 178 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 645620400 is about 25409.0613758163. The cubic root of 645620400 is about 864.2891907452.

Adding to 645620400 its reverse (4026546), we get a palindrome (649646946).

The spelling of 645620400 in words is "six hundred forty-five million, six hundred twenty thousand, four hundred".