643540234843 has 4 divisors (see below), whose sum is σ = 702043892568. Its totient is φ = 585036577120.

The previous prime is 643540234837. The next prime is 643540234979. The reversal of 643540234843 is 348432045346.

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

It is a cyclic number.

It is not a de Polignac number, because 643540234843 - 2²¹ = 643538137691 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643540234793 and 643540234802.

It is not an unprimeable number, because it can be changed into a prime (643540234823) 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, 29251828846 + ... + 29251828867.

It is an arithmetic number, because the mean of its divisors is an integer number (175510973142).

Almost surely, 2^643540234843 is an apocalyptic number.

643540234843 is a deficient number, since it is larger than the sum of its proper divisors (58503657725).

643540234843 is a wasteful number, since it uses less digits than its factorization.

643540234843 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58503657724.

The product of its (nonzero) digits is 3317760, while the sum is 46.

The spelling of 643540234843 in words is "six hundred forty-three billion, five hundred forty million, two hundred thirty-four thousand, eight hundred forty-three".