198521865641 has 4 divisors (see below), whose sum is σ = 216569307984. Its totient is φ = 180474423300.

The previous prime is 198521865637. The next prime is 198521865667. The reversal of 198521865641 is 146568125891.

198521865641 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 198521865641 - 2² = 198521865637 is a prime.

It is a super-2 number, since 2×198521865641² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (198521865601) 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 3 ways as a sum of consecutive naturals, for example, 9023721155 + ... + 9023721176.

It is an arithmetic number, because the mean of its divisors is an integer number (54142326996).

Almost surely, 2^198521865641 is an apocalyptic number.

198521865641 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

198521865641 is a deficient number, since it is larger than the sum of its proper divisors (18047442343).

198521865641 is a wasteful number, since it uses less digits than its factorization.

198521865641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18047442342.

The product of its digits is 4147200, while the sum is 56.

The spelling of 198521865641 in words is "one hundred ninety-eight billion, five hundred twenty-one million, eight hundred sixty-five thousand, six hundred forty-one".