646424196181 has 4 divisors (see below), whose sum is σ = 647448640864. Its totient is φ = 645399751500.

The previous prime is 646424196157. The next prime is 646424196247. The reversal of 646424196181 is 181691424646.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 181691424646 = 2 ⋅90845712323.

It is a cyclic number.

It is not a de Polignac number, because 646424196181 - 2¹⁹ = 646423671893 is a prime.

It is a super-2 number, since 2×646424196181² (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 (646424196101) 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, 512221395 + ... + 512222656.

It is an arithmetic number, because the mean of its divisors is an integer number (161862160216).

Almost surely, 2^646424196181 is an apocalyptic number.

It is an amenable number.

646424196181 is a deficient number, since it is larger than the sum of its proper divisors (1024444683).

646424196181 is a wasteful number, since it uses less digits than its factorization.

646424196181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1024444682.

The product of its digits is 1990656, while the sum is 52.

The spelling of 646424196181 in words is "six hundred forty-six billion, four hundred twenty-four million, one hundred ninety-six thousand, one hundred eighty-one".