645767 has 4 divisors (see below), whose sum is σ = 647976. Its totient is φ = 643560.

The previous prime is 645763. The next prime is 645787. The reversal of 645767 is 767546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645767 - 2² = 645763 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645767.

It is not an unprimeable number, because it can be changed into a prime (645763) 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, 584 + ... + 1277.

It is an arithmetic number, because the mean of its divisors is an integer number (161994).

2⁶⁴⁵⁷⁶⁷ is an apocalyptic number.

645767 is a deficient number, since it is larger than the sum of its proper divisors (2209).

645767 is a wasteful number, since it uses less digits than its factorization.

645767 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2208.

The product of its digits is 35280, while the sum is 35.

The square root of 645767 is about 803.5962916789. The cubic root of 645767 is about 86.4354603386.

The spelling of 645767 in words is "six hundred forty-five thousand, seven hundred sixty-seven".