645199 has 4 divisors (see below), whose sum is σ = 648736. Its totient is φ = 641664.

The previous prime is 645187. The next prime is 645233. The reversal of 645199 is 991546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 991546 = 2 ⋅495773.

It is a cyclic number.

It is not a de Polignac number, because 645199 - 2⁹ = 644687 is a prime.

It is a Duffinian number.

645199 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645149) 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, 1479 + ... + 1864.

It is an arithmetic number, because the mean of its divisors is an integer number (162184).

2⁶⁴⁵¹⁹⁹ is an apocalyptic number.

645199 is a deficient number, since it is larger than the sum of its proper divisors (3537).

645199 is a wasteful number, since it uses less digits than its factorization.

645199 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3536.

The product of its digits is 9720, while the sum is 34.

The square root of 645199 is about 803.2428026444. The cubic root of 645199 is about 86.4101107709.

The spelling of 645199 in words is "six hundred forty-five thousand, one hundred ninety-nine".