198778021641 has 24 divisors (see below), whose sum is σ = 302953597440. Its totient is φ = 125245764000.

The previous prime is 198778021633. The next prime is 198778021691. The reversal of 198778021641 is 146120877891.

It is not a de Polignac number, because 198778021641 - 2³ = 198778021633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (198778021601) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1308585 + ... + 1452566.

It is an arithmetic number, because the mean of its divisors is an integer number (12623066560).

Almost surely, 2^198778021641 is an apocalyptic number.

It is an amenable number.

198778021641 is a deficient number, since it is larger than the sum of its proper divisors (104175575799).

198778021641 is a wasteful number, since it uses less digits than its factorization.

198778021641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2761597 (or 2761594 counting only the distinct ones).

The product of its (nonzero) digits is 1354752, while the sum is 54.

The spelling of 198778021641 in words is "one hundred ninety-eight billion, seven hundred seventy-eight million, twenty-one thousand, six hundred forty-one".