43872821 has 2 divisors, whose sum is σ = 43872822. Its totient is φ = 43872820.

The previous prime is 43872793. The next prime is 43872823. The reversal of 43872821 is 12827834.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 32890225 + 10982596 = 5735^2 + 3314^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-43872821 is a prime.

Together with 43872823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (43872823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21936410 + 21936411.

It is an arithmetic number, because the mean of its divisors is an integer number (21936411).

Almost surely, 2^43872821 is an apocalyptic number.

It is an amenable number.

43872821 is a deficient number, since it is larger than the sum of its proper divisors (1).

43872821 is an equidigital number, since it uses as much as digits as its factorization.

43872821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21504, while the sum is 35.

The square root of 43872821 is about 6623.6561655931. The cubic root of 43872821 is about 352.6943642486.

The spelling of 43872821 in words is "forty-three million, eight hundred seventy-two thousand, eight hundred twenty-one".