643553 has 2 divisors, whose sum is σ = 643554. Its totient is φ = 643552.

The previous prime is 643547. The next prime is 643567. The reversal of 643553 is 355346.

643553 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 529984 + 113569 = 728^2 + 337^2 .

It is a cyclic number.

It is not a de Polignac number, because 643553 - 2¹⁰ = 642529 is a prime.

It is not a weakly prime, because it can be changed into another prime (643523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321776 + 321777.

It is an arithmetic number, because the mean of its divisors is an integer number (321777).

2⁶⁴³⁵⁵³ is an apocalyptic number.

It is an amenable number.

643553 is a deficient number, since it is larger than the sum of its proper divisors (1).

643553 is an equidigital number, since it uses as much as digits as its factorization.

643553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5400, while the sum is 26.

The square root of 643553 is about 802.2175515407. The cubic root of 643553 is about 86.3365664510.

Adding to 643553 its reverse (355346), we get a palindrome (998899).

The spelling of 643553 in words is "six hundred forty-three thousand, five hundred fifty-three".