21047563 has 2 divisors, whose sum is σ = 21047564. Its totient is φ = 21047562.

The previous prime is 21047539. The next prime is 21047567. The reversal of 21047563 is 36574012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21047563 - 2⁵ = 21047531 is a prime.

It is not a weakly prime, because it can be changed into another prime (21047567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10523781 + 10523782.

It is an arithmetic number, because the mean of its divisors is an integer number (10523782).

Almost surely, 2^21047563 is an apocalyptic number.

21047563 is a deficient number, since it is larger than the sum of its proper divisors (1).

21047563 is an equidigital number, since it uses as much as digits as its factorization.

21047563 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21047563 is about 4587.7623085770. The cubic root of 21047563 is about 276.1005506002.

The spelling of 21047563 in words is "twenty-one million, forty-seven thousand, five hundred sixty-three".