1643781198820 has 96 divisors (see below), whose sum is σ = 3619709710848. Its totient is φ = 626407444992.

The previous prime is 1643781198811. The next prime is 1643781198821. The reversal of 1643781198820 is 288911873461.

It is not an unprimeable number, because it can be changed into a prime (1643781198821) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11773662 + ... + 11912458.

It is an arithmetic number, because the mean of its divisors is an integer number (37705309488).

Almost surely, 2^{1643781198820} is an apocalyptic number.

1643781198820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1643781198820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1809854855424).

1643781198820 is an abundant number, since it is smaller than the sum of its proper divisors (1975928512028).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1643781198820 is a wasteful number, since it uses less digits than its factorization.

1643781198820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139189 (or 139187 counting only the distinct ones).

The product of its (nonzero) digits is 4644864, while the sum is 58.

The spelling of 1643781198820 in words is "one trillion, six hundred forty-three billion, seven hundred eighty-one million, one hundred ninety-eight thousand, eight hundred twenty".