645815 has 8 divisors (see below), whose sum is σ = 779760. Its totient is φ = 513472.

The previous prime is 645803. The next prime is 645833. The reversal of 645815 is 518546.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645815 - 2⁶ = 645751 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 851 + ... + 1419.

It is an arithmetic number, because the mean of its divisors is an integer number (97470).

2⁶⁴⁵⁸¹⁵ is an apocalyptic number.

645815 is a deficient number, since it is larger than the sum of its proper divisors (133945).

645815 is a wasteful number, since it uses less digits than its factorization.

645815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 801.

The product of its digits is 4800, while the sum is 29.

The square root of 645815 is about 803.6261568665. The cubic root of 645815 is about 86.4376018743.

The spelling of 645815 in words is "six hundred forty-five thousand, eight hundred fifteen".