643440493 has 2 divisors, whose sum is σ = 643440494. Its totient is φ = 643440492.

The previous prime is 643440467. The next prime is 643440509. The reversal of 643440493 is 394044346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 383650569 + 259789924 = 19587^2 + 16118^2 .

It is a cyclic number.

It is not a de Polignac number, because 643440493 - 2¹³ = 643432301 is a prime.

It is a super-3 number, since 3×643440493³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643440443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321720246 + 321720247.

It is an arithmetic number, because the mean of its divisors is an integer number (321720247).

Almost surely, 2^643440493 is an apocalyptic number.

It is an amenable number.

643440493 is a deficient number, since it is larger than the sum of its proper divisors (1).

643440493 is an equidigital number, since it uses as much as digits as its factorization.

643440493 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 124416, while the sum is 37.

The square root of 643440493 is about 25366.1288532563. The cubic root of 643440493 is about 863.3153499067.

The spelling of 643440493 in words is "six hundred forty-three million, four hundred forty thousand, four hundred ninety-three".