21505063 has 2 divisors, whose sum is σ = 21505064. Its totient is φ = 21505062.

The previous prime is 21505039. The next prime is 21505109. The reversal of 21505063 is 36050512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21505063 - 2¹⁷ = 21373991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21505013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10752531 + 10752532.

It is an arithmetic number, because the mean of its divisors is an integer number (10752532).

Almost surely, 2^21505063 is an apocalyptic number.

21505063 is a deficient number, since it is larger than the sum of its proper divisors (1).

21505063 is an equidigital number, since it uses as much as digits as its factorization.

21505063 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 900, while the sum is 22.

The square root of 21505063 is about 4637.3551729407. The cubic root of 21505063 is about 278.0867136289.

Adding to 21505063 its reverse (36050512), we get a palindrome (57555575).

The spelling of 21505063 in words is "twenty-one million, five hundred five thousand, sixty-three".