645966 has 24 divisors (see below), whose sum is σ = 1482624. Its totient is φ = 202560.

The previous prime is 645941. The next prime is 645973. The reversal of 645966 is 669546.

It is a happy number.

645966 is a `hidden beast` number, since 64 + 596 + 6 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 645966.

It is a congruent number.

It is an unprimeable number.

645966 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 750 + ... + 1361.

It is an arithmetic number, because the mean of its divisors is an integer number (61776).

2⁶⁴⁵⁹⁶⁶ is an apocalyptic number.

645966 is an abundant number, since it is smaller than the sum of its proper divisors (836658).

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

645966 is a wasteful number, since it uses less digits than its factorization.

645966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2136 (or 2133 counting only the distinct ones).

The product of its digits is 38880, while the sum is 36.

The square root of 645966 is about 803.7201005325. The cubic root of 645966 is about 86.4443380969. Note that the first 3 decimals are identical.

The spelling of 645966 in words is "six hundred forty-five thousand, nine hundred sixty-six".