645906240 has 504 divisors, whose sum is σ = 2710281600. Its totient is φ = 140507136.

The previous prime is 645906227. The next prime is 645906253. The reversal of 645906240 is 42609546.

645906240 is a `hidden beast` number, since 6 + 4 + 590 + 62 + 4 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (645906227) and next prime (645906253).

It is a tau number, because it is divible by the number of its divisors (504).

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 = 645906195 and 645906204.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 3245661 + ... + 3245859.

Almost surely, 2^645906240 is an apocalyptic number.

645906240 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 645906240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1355140800).

645906240 is an abundant number, since it is smaller than the sum of its proper divisors (2064375360).

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

645906240 is a wasteful number, since it uses less digits than its factorization.

645906240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259 (or 239 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 645906240 is about 25414.6855184163. The cubic root of 645906240 is about 864.4167228430.

The spelling of 645906240 in words is "six hundred forty-five million, nine hundred six thousand, two hundred forty".