645784 has 16 divisors (see below), whose sum is σ = 1225800. Its totient is φ = 318912.

The previous prime is 645763. The next prime is 645787. The reversal of 645784 is 487546.

645784 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 259 + ... + 1165.

2⁶⁴⁵⁷⁸⁴ is an apocalyptic number.

It is an amenable number.

645784 is a deficient number, since it is larger than the sum of its proper divisors (580016).

645784 is a wasteful number, since it uses less digits than its factorization.

645784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1002 (or 998 counting only the distinct ones).

The product of its digits is 26880, while the sum is 34.

The square root of 645784 is about 803.6068690597. The cubic root of 645784 is about 86.4362188113.

The spelling of 645784 in words is "six hundred forty-five thousand, seven hundred eighty-four".