643725440131 has 16 divisors (see below), whose sum is σ = 664825125888. Its totient is φ = 622885939200.

The previous prime is 643725440077. The next prime is 643725440173. The reversal of 643725440131 is 131044527346.

It is a cyclic number.

It is not a de Polignac number, because 643725440131 - 2⁹ = 643725439619 is a prime.

It is a super-2 number, since 2×643725440131² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643725441131) 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 in 15 ways as a sum of consecutive naturals, for example, 18420531 + ... + 18455443.

It is an arithmetic number, because the mean of its divisors is an integer number (41551570368).

Almost surely, 2^643725440131 is an apocalyptic number.

643725440131 is a deficient number, since it is larger than the sum of its proper divisors (21099685757).

643725440131 is a wasteful number, since it uses less digits than its factorization.

643725440131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38622.

The product of its (nonzero) digits is 241920, while the sum is 40.

Adding to 643725440131 its reverse (131044527346), we get a palindrome (774769967477).

The spelling of 643725440131 in words is "six hundred forty-three billion, seven hundred twenty-five million, four hundred forty thousand, one hundred thirty-one".