645884 has 6 divisors (see below), whose sum is σ = 1130304. Its totient is φ = 322940.

The previous prime is 645877. The next prime is 645889. The reversal of 645884 is 488546.

It is a super-2 number, since 2×645884² = 834332282912, which contains 22 as substring.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645884.

It is not an unprimeable number, because it can be changed into a prime (645889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80732 + ... + 80739.

It is an arithmetic number, because the mean of its divisors is an integer number (188384).

2⁶⁴⁵⁸⁸⁴ is an apocalyptic number.

It is an amenable number.

645884 is a deficient number, since it is larger than the sum of its proper divisors (484420).

645884 is a wasteful number, since it uses less digits than its factorization.

645884 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161475 (or 161473 counting only the distinct ones).

The product of its digits is 30720, while the sum is 35.

The square root of 645884 is about 803.6690861294. The cubic root of 645884 is about 86.4406801461.

The spelling of 645884 in words is "six hundred forty-five thousand, eight hundred eighty-four".