1943839921 has 3 divisors (see below), whose sum is σ = 1943884011. Its totient is φ = 1943795832.

The previous prime is 1943839867. The next prime is 1943839949. The reversal of 1943839921 is 1299383491.

The square root of 1943839921 is 44089.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 878470321 + 1065369600 = 29639^2 + 32640^2 .

It is not a de Polignac number, because 1943839921 - 2⁹ = 1943839409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1943839321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 22045 + ... + 66133.

It is an arithmetic number, because the mean of its divisors is an integer number (647961337).

Almost surely, 2^1943839921 is an apocalyptic number.

1943839921 is the 44089-th square number.

1943839921 is the 22045-th centered octagonal number.

It is an amenable number.

1943839921 is a deficient number, since it is larger than the sum of its proper divisors (44090).

1943839921 is an frugal number, since it uses more digits than its factorization.

1943839921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88178 (or 44089 counting only the distinct ones).

The product of its digits is 419904, while the sum is 49.

The cubic root of 1943839921 is about 1248.0160359218.

Multiplying 1943839921 by its sum of digits (49), we get a square (95248156129 = 308623²).

Multiplying 1943839921 by its product of digits (419904), we get a square (816226158187584 = 28569672²).

It can be divided in two parts, 194383 and 9921, that added together give a square (204304 = 452²).

The spelling of 1943839921 in words is "one billion, nine hundred forty-three million, eight hundred thirty-nine thousand, nine hundred twenty-one".