643919 has 2 divisors, whose sum is σ = 643920. Its totient is φ = 643918.

The previous prime is 643889. The next prime is 643927. The reversal of 643919 is 919346.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643919 is a prime.

It is a super-2 number, since 2×643919² = 829263357122, which contains 22 as substring.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321959 + 321960.

It is an arithmetic number, because the mean of its divisors is an integer number (321960).

2⁶⁴³⁹¹⁹ is an apocalyptic number.

643919 is a deficient number, since it is larger than the sum of its proper divisors (1).

643919 is an equidigital number, since it uses as much as digits as its factorization.

643919 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5832, while the sum is 32.

The square root of 643919 is about 802.4456367879. The cubic root of 643919 is about 86.3529303946.

The spelling of 643919 in words is "six hundred forty-three thousand, nine hundred nineteen".