645886800 has 360 divisors, whose sum is σ = 2485707224. Its totient is φ = 154275840.

The previous prime is 645886799. The next prime is 645886807. The reversal of 645886800 is 8688546.

645886800 is a `hidden beast` number, since 6 + 4 + 588 + 68 + 0 + 0 = 666.

It can be written as a sum of positive squares in 12 ways, for example, as 138015504 + 507871296 = 11748^2 + 22536^2 .

It is a tau number, because it is divible by the number of its divisors (360).

It is a super-3 number, since 3×645886800³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645886807) 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 71 ways as a sum of consecutive naturals, for example, 1731414 + ... + 1731786.

Almost surely, 2^645886800 is an apocalyptic number.

645886800 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 645886800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1242853612).

645886800 is an abundant number, since it is smaller than the sum of its proper divisors (1839820424).

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

645886800 is a wasteful number, since it uses less digits than its factorization.

645886800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 447 (or 433 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 45.

The square root of 645886800 is about 25414.3030594978. The cubic root of 645886800 is about 864.4080505680.

The spelling of 645886800 in words is "six hundred forty-five million, eight hundred eighty-six thousand, eight hundred".