643423447 has 4 divisors (see below), whose sum is σ = 644207976. Its totient is φ = 642638920.

The previous prime is 643423439. The next prime is 643423457. The reversal of 643423447 is 744324346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 744324346 = 2 ⋅372162173.

It is a cyclic number.

It is not a de Polignac number, because 643423447 - 2³ = 643423439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643423457) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 391033 + ... + 392674.

It is an arithmetic number, because the mean of its divisors is an integer number (161051994).

Almost surely, 2^643423447 is an apocalyptic number.

643423447 is a deficient number, since it is larger than the sum of its proper divisors (784529).

643423447 is an equidigital number, since it uses as much as digits as its factorization.

643423447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 784528.

The product of its digits is 193536, while the sum is 37.

The square root of 643423447 is about 25365.7928517916. The cubic root of 643423447 is about 863.3077262008.

The spelling of 643423447 in words is "six hundred forty-three million, four hundred twenty-three thousand, four hundred forty-seven".