645704 has 8 divisors (see below), whose sum is σ = 1210710. Its totient is φ = 322848.

The previous prime is 645703. The next prime is 645713. The reversal of 645704 is 407546.

It can be written as a sum of positive squares in only one way, i.e., 643204 + 2500 = 802^2 + 50^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (645703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40349 + ... + 40364.

2⁶⁴⁵⁷⁰⁴ is an apocalyptic number.

It is an amenable number.

645704 is a deficient number, since it is larger than the sum of its proper divisors (565006).

645704 is a wasteful number, since it uses less digits than its factorization.

645704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80719 (or 80715 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 26.

The square root of 645704 is about 803.5570919356. The cubic root of 645704 is about 86.4326494119.

The spelling of 645704 in words is "six hundred forty-five thousand, seven hundred four".