643233541 has 2 divisors, whose sum is σ = 643233542. Its totient is φ = 643233540.

The previous prime is 643233533. The next prime is 643233559. The reversal of 643233541 is 145332346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 622302916 + 20930625 = 24946^2 + 4575^2 .

It is a cyclic number.

It is not a de Polignac number, because 643233541 - 2³ = 643233533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643233511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321616770 + 321616771.

It is an arithmetic number, because the mean of its divisors is an integer number (321616771).

Almost surely, 2^643233541 is an apocalyptic number.

It is an amenable number.

643233541 is a deficient number, since it is larger than the sum of its proper divisors (1).

643233541 is an equidigital number, since it uses as much as digits as its factorization.

643233541 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 31.

The square root of 643233541 is about 25362.0492271425. The cubic root of 643233541 is about 863.2227829439. Note that the first 3 decimals are identical.

Adding to 643233541 its reverse (145332346), we get a palindrome (788565887).

The spelling of 643233541 in words is "six hundred forty-three million, two hundred thirty-three thousand, five hundred forty-one".