645659 has 4 divisors (see below), whose sum is σ = 737904. Its totient is φ = 553416.

The previous prime is 645649. The next prime is 645661. The reversal of 645659 is 956546.

645659 = T₄₂₆ + T₄₂₇ + ... + T₄₃₂.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 956546 = 2 ⋅478273.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645659 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645659.

It is not an unprimeable number, because it can be changed into a prime (645629) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 46112 + ... + 46125.

It is an arithmetic number, because the mean of its divisors is an integer number (184476).

2⁶⁴⁵⁶⁵⁹ is an apocalyptic number.

645659 is a deficient number, since it is larger than the sum of its proper divisors (92245).

645659 is an equidigital number, since it uses as much as digits as its factorization.

645659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92244.

The product of its digits is 32400, while the sum is 35.

The square root of 645659 is about 803.5290909482. The cubic root of 645659 is about 86.4306414952.

The spelling of 645659 in words is "six hundred forty-five thousand, six hundred fifty-nine".