21043747 has 2 divisors, whose sum is σ = 21043748. Its totient is φ = 21043746.

The previous prime is 21043691. The next prime is 21043753. The reversal of 21043747 is 74734012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21043747 is a prime.

It is a Chen prime.

It is equal to p_1332586 and since 21043747 and 1332586 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21041747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521873 + 10521874.

It is an arithmetic number, because the mean of its divisors is an integer number (10521874).

Almost surely, 2^21043747 is an apocalyptic number.

21043747 is a deficient number, since it is larger than the sum of its proper divisors (1).

21043747 is an equidigital number, since it uses as much as digits as its factorization.

21043747 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4704, while the sum is 28.

The square root of 21043747 is about 4587.3464006983. The cubic root of 21043747 is about 276.0838635791.

Adding to 21043747 its reverse (74734012), we get a palindrome (95777759).

The spelling of 21043747 in words is "twenty-one million, forty-three thousand, seven hundred forty-seven".