43620821 has 2 divisors, whose sum is σ = 43620822. Its totient is φ = 43620820.

The previous prime is 43620781. The next prime is 43620823. The reversal of 43620821 is 12802634.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 43428100 + 192721 = 6590^2 + 439^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-43620821 is a prime.

Together with 43620823, 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 (43620823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21810410 + 21810411.

It is an arithmetic number, because the mean of its divisors is an integer number (21810411).

Almost surely, 2^43620821 is an apocalyptic number.

It is an amenable number.

43620821 is a deficient number, since it is larger than the sum of its proper divisors (1).

43620821 is an equidigital number, since it uses as much as digits as its factorization.

43620821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 43620821 is about 6604.6060442694. The cubic root of 43620821 is about 352.0177897560.

The spelling of 43620821 in words is "forty-three million, six hundred twenty thousand, eight hundred twenty-one".