643534042 has 4 divisors (see below), whose sum is σ = 965301066. Its totient is φ = 321767020.

The previous prime is 643534037. The next prime is 643534049. The reversal of 643534042 is 240435346.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 354907921 + 288626121 = 18839^2 + 16989^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 643533995 and 643534013.

It is not an unprimeable number, because it can be changed into a prime (643534049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160883509 + ... + 160883512.

Almost surely, 2^643534042 is an apocalyptic number.

643534042 is a deficient number, since it is larger than the sum of its proper divisors (321767024).

643534042 is a wasteful number, since it uses less digits than its factorization.

643534042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321767023.

The product of its (nonzero) digits is 34560, while the sum is 31.

The square root of 643534042 is about 25367.9727609441. The cubic root of 643534042 is about 863.3571866551.

Adding to 643534042 its reverse (240435346), we get a palindrome (883969388).

The spelling of 643534042 in words is "six hundred forty-three million, five hundred thirty-four thousand, forty-two".