643440401231 has 4 divisors (see below), whose sum is σ = 643470675000. Its totient is φ = 643410127464.

The previous prime is 643440401089. The next prime is 643440401251. The reversal of 643440401231 is 132104044346.

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 643440401231 - 2³⁴ = 626260532047 is a prime.

It is a super-2 number, since 2×643440401231² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643440401251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15104981 + ... + 15147518.

It is an arithmetic number, because the mean of its divisors is an integer number (160867668750).

Almost surely, 2^643440401231 is an apocalyptic number.

643440401231 is a deficient number, since it is larger than the sum of its proper divisors (30273769).

643440401231 is a wasteful number, since it uses less digits than its factorization.

643440401231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30273768.

The product of its (nonzero) digits is 27648, while the sum is 32.

Adding to 643440401231 its reverse (132104044346), we get a palindrome (775544445577).

The spelling of 643440401231 in words is "six hundred forty-three billion, four hundred forty million, four hundred one thousand, two hundred thirty-one".