1821951941209 has 15 divisors (see below), whose sum is σ = 1882380142335. Its totient is φ = 1763428792680.

The previous prime is 1821951941177. The next prime is 1821951941219. The reversal of 1821951941209 is 9021491591281.

The square root of 1821951941209 is 1349797.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 1630307617225 + 191644323984 = 1276835^2 + 437772^2 .

It is not a de Polignac number, because 1821951941209 - 2⁵ = 1821951941177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1821951941219) 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 14 ways as a sum of consecutive naturals, for example, 9539015304 + ... + 9539015494.

It is an arithmetic number, because the mean of its divisors is an integer number (125492009489).

Almost surely, 2^{1821951941209} is an apocalyptic number.

1821951941209 is the 1349797-th square number.

1821951941209 is the 674899-th centered octagonal number.

It is an amenable number.

1821951941209 is a deficient number, since it is larger than the sum of its proper divisors (60428201126).

1821951941209 is an frugal number, since it uses more digits than its factorization.

1821951941209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 838 (or 228 counting only the distinct ones).

The product of its (nonzero) digits is 466560, while the sum is 52.

The spelling of 1821951941209 in words is "one trillion, eight hundred twenty-one billion, nine hundred fifty-one million, nine hundred forty-one thousand, two hundred nine".