643922258181 has 16 divisors (see below), whose sum is σ = 909353808000. Its totient is φ = 403902056448.

The previous prime is 643922258153. The next prime is 643922258209. The reversal of 643922258181 is 181852229346.

It is an interprime number because it is at equal distance from previous prime (643922258153) and next prime (643922258209).

It is not a de Polignac number, because 643922258181 - 2⁶ = 643922258117 is a prime.

It is a super-4 number, since 4×643922258181⁴ (a number of 48 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643922258141) 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 15 ways as a sum of consecutive naturals, for example, 1830481 + ... + 2153718.

It is an arithmetic number, because the mean of its divisors is an integer number (56834613000).

Almost surely, 2^643922258181 is an apocalyptic number.

It is an amenable number.

643922258181 is a deficient number, since it is larger than the sum of its proper divisors (265431549819).

643922258181 is a wasteful number, since it uses less digits than its factorization.

643922258181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3987388.

The product of its digits is 1658880, while the sum is 51.

The spelling of 643922258181 in words is "six hundred forty-three billion, nine hundred twenty-two million, two hundred fifty-eight thousand, one hundred eighty-one".