43816721 has 4 divisors (see below), whose sum is σ = 47187252. Its totient is φ = 40446192.

The previous prime is 43816697. The next prime is 43816723. The reversal of 43816721 is 12761834.

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 27300625 + 16516096 = 5225^2 + 4064^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-43816721 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (43816723) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1685246 + ... + 1685271.

It is an arithmetic number, because the mean of its divisors is an integer number (11796813).

Almost surely, 2^43816721 is an apocalyptic number.

It is an amenable number.

43816721 is a deficient number, since it is larger than the sum of its proper divisors (3370531).

43816721 is a wasteful number, since it uses less digits than its factorization.

43816721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3370530.

The product of its digits is 8064, while the sum is 32.

The square root of 43816721 is about 6619.4199896970. The cubic root of 43816721 is about 352.5439705054.

The spelling of 43816721 in words is "forty-three million, eight hundred sixteen thousand, seven hundred twenty-one".