43781921 has 4 divisors (see below), whose sum is σ = 44183700. Its totient is φ = 43380144.

The previous prime is 43781917. The next prime is 43781923. The reversal of 43781921 is 12918734.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19140625 + 24641296 = 4375^2 + 4964^2 .

It is a cyclic number.

It is not a de Polignac number, because 43781921 - 2² = 43781917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (43781923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 200726 + ... + 200943.

It is an arithmetic number, because the mean of its divisors is an integer number (11045925).

Almost surely, 2^43781921 is an apocalyptic number.

It is an amenable number.

43781921 is a deficient number, since it is larger than the sum of its proper divisors (401779).

43781921 is a wasteful number, since it uses less digits than its factorization.

43781921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401778.

The product of its digits is 12096, while the sum is 35.

The square root of 43781921 is about 6616.7908384654. The cubic root of 43781921 is about 352.4506136066.

The spelling of 43781921 in words is "forty-three million, seven hundred eighty-one thousand, nine hundred twenty-one".