421561198181 has 4 divisors (see below), whose sum is σ = 439889945952. Its totient is φ = 403232450412.

The previous prime is 421561198171. The next prime is 421561198207. The reversal of 421561198181 is 181891165124.

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.

It is a cyclic number.

It is not a de Polignac number, because 421561198181 - 2¹⁰ = 421561197157 is a prime.

It is a super-2 number, since 2×421561198181² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (421561198111) 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, 9164373851 + ... + 9164373896.

It is an arithmetic number, because the mean of its divisors is an integer number (109972486488).

Almost surely, 2^421561198181 is an apocalyptic number.

It is an amenable number.

421561198181 is a deficient number, since it is larger than the sum of its proper divisors (18328747771).

421561198181 is a wasteful number, since it uses less digits than its factorization.

421561198181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18328747770.

The product of its digits is 138240, while the sum is 47.

The spelling of 421561198181 in words is "four hundred twenty-one billion, five hundred sixty-one million, one hundred ninety-eight thousand, one hundred eighty-one".