645970 has 16 divisors (see below), whose sum is σ = 1252440. Its totient is φ = 238464.

The previous prime is 645941. The next prime is 645973. The reversal of 645970 is 79546.

It can be written as a sum of positive squares in 4 ways, for example, as 301401 + 344569 = 549^2 + 587^2 .

It is not an unprimeable number, because it can be changed into a prime (645973) by changing a digit.

645970 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2355 + ... + 2614.

2⁶⁴⁵⁹⁷⁰ is an apocalyptic number.

645970 is a deficient number, since it is larger than the sum of its proper divisors (606470).

645970 is a wasteful number, since it uses less digits than its factorization.

645970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4989.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 645970 is about 803.7225889572. The cubic root of 645970 is about 86.4445165256. Note that the first 3 decimals are identical.

The spelling of 645970 in words is "six hundred forty-five thousand, nine hundred seventy".