645566040 has 384 divisors, whose sum is σ = 2568384000. Its totient is φ = 137355264.

The previous prime is 645566029. The next prime is 645566069. The reversal of 645566040 is 40665546.

It is a happy number.

645566040 is a `hidden beast` number, since 6 + 4 + 556 + 60 + 40 = 666.

645566040 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a junction number, because it is equal to n+sod(n) for n = 645565986 and 645566004.

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, 4644291 + ... + 4644429.

It is an arithmetic number, because the mean of its divisors is an integer number (6688500).

Almost surely, 2^645566040 is an apocalyptic number.

645566040 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 645566040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1284192000).

645566040 is an abundant number, since it is smaller than the sum of its proper divisors (1922817960).

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

645566040 is a wasteful number, since it uses less digits than its factorization.

645566040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 279 (or 272 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 36.

The square root of 645566040 is about 25407.9916561699. The cubic root of 645566040 is about 864.2649329000.

The spelling of 645566040 in words is "six hundred forty-five million, five hundred sixty-six thousand, forty".