21047441 has 2 divisors, whose sum is σ = 21047442. Its totient is φ = 21047440.

The previous prime is 21047431. The next prime is 21047443. The reversal of 21047441 is 14474012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17606416 + 3441025 = 4196^2 + 1855^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21047441 is a prime.

It is a Sophie Germain prime.

Together with 21047443, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21047443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10523720 + 10523721.

It is an arithmetic number, because the mean of its divisors is an integer number (10523721).

Almost surely, 2^21047441 is an apocalyptic number.

It is an amenable number.

21047441 is a deficient number, since it is larger than the sum of its proper divisors (1).

21047441 is an equidigital number, since it uses as much as digits as its factorization.

21047441 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 23.

The square root of 21047441 is about 4587.7490123153. The cubic root of 21047441 is about 276.1000171365.

The spelling of 21047441 in words is "twenty-one million, forty-seven thousand, four hundred forty-one".