643548745531 has 4 divisors (see below), whose sum is σ = 644137537792. Its totient is φ = 642959953272.

The previous prime is 643548745523. The next prime is 643548745549. The reversal of 643548745531 is 135547845346.

It is a happy number.

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 643548745531 - 2³ = 643548745523 is a prime.

It is a super-2 number, since 2×643548745531² (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 (643548745561) 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, 294394491 + ... + 294396676.

It is an arithmetic number, because the mean of its divisors is an integer number (161034384448).

Almost surely, 2^643548745531 is an apocalyptic number.

643548745531 is a deficient number, since it is larger than the sum of its proper divisors (588792261).

643548745531 is a wasteful number, since it uses less digits than its factorization.

643548745531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 588792260.

The product of its digits is 24192000, while the sum is 55.

The spelling of 643548745531 in words is "six hundred forty-three billion, five hundred forty-eight million, seven hundred forty-five thousand, five hundred thirty-one".