643633 has 2 divisors, whose sum is σ = 643634. Its totient is φ = 643632.

The previous prime is 643619. The next prime is 643639. The reversal of 643633 is 336346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 419904 + 223729 = 648^2 + 473^2 .

It is a cyclic number.

It is not a de Polignac number, because 643633 - 2⁹ = 643121 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643598 and 643607.

It is not a weakly prime, because it can be changed into another prime (643639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321816 + 321817.

It is an arithmetic number, because the mean of its divisors is an integer number (321817).

2⁶⁴³⁶³³ is an apocalyptic number.

It is an amenable number.

643633 is a deficient number, since it is larger than the sum of its proper divisors (1).

643633 is an equidigital number, since it uses as much as digits as its factorization.

643633 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 25.

The square root of 643633 is about 802.2674117774. The cubic root of 643633 is about 86.3401437990.

Adding to 643633 its reverse (336346), we get a palindrome (979979).

The spelling of 643633 in words is "six hundred forty-three thousand, six hundred thirty-three".