643799 has 4 divisors (see below), whose sum is σ = 693336. Its totient is φ = 594264.

The previous prime is 643781. The next prime is 643847. The reversal of 643799 is 997346.

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 643799 - 2¹² = 639703 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 (643729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24749 + ... + 24774.

It is an arithmetic number, because the mean of its divisors is an integer number (173334).

2⁶⁴³⁷⁹⁹ is an apocalyptic number.

643799 is a deficient number, since it is larger than the sum of its proper divisors (49537).

643799 is a wasteful number, since it uses less digits than its factorization.

643799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49536.

The product of its digits is 40824, while the sum is 38.

The square root of 643799 is about 802.3708618837. The cubic root of 643799 is about 86.3475658506.

The spelling of 643799 in words is "six hundred forty-three thousand, seven hundred ninety-nine".