645806840 has 32 divisors (see below), whose sum is σ = 1660646880. Its totient is φ = 221419392.

The previous prime is 645806831. The next prime is 645806851. The reversal of 645806840 is 48608546.

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1152947 + ... + 1153506.

It is an arithmetic number, because the mean of its divisors is an integer number (51895215).

Almost surely, 2^645806840 is an apocalyptic number.

It is an amenable number.

645806840 is an abundant number, since it is smaller than the sum of its proper divisors (1014840040).

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

645806840 is a wasteful number, since it uses less digits than its factorization.

645806840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2306471 (or 2306467 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 41.

The square root of 645806840 is about 25412.7298809081. The cubic root of 645806840 is about 864.3723782076.

It can be divided in two parts, 645806 and 840, that added together give a palindrome (646646).

The spelling of 645806840 in words is "six hundred forty-five million, eight hundred six thousand, eight hundred forty".