645791 has 8 divisors (see below), whose sum is σ = 697200. Its totient is φ = 596160.

The previous prime is 645787. The next prime is 645803. The reversal of 645791 is 197546.

It is a happy number.

645791 is nontrivially palindromic in base 5.

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 645791 - 2² = 645787 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645751) by changing a digit.

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, 365 + ... + 1193.

It is an arithmetic number, because the mean of its divisors is an integer number (87150).

2⁶⁴⁵⁷⁹¹ is an apocalyptic number.

645791 is a deficient number, since it is larger than the sum of its proper divisors (51409).

645791 is a wasteful number, since it uses less digits than its factorization.

645791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 889.

The product of its digits is 7560, while the sum is 32.

The square root of 645791 is about 803.6112244114. The cubic root of 645791 is about 86.4365311197.

The spelling of 645791 in words is "six hundred forty-five thousand, seven hundred ninety-one".