21730459 has 2 divisors, whose sum is σ = 21730460. Its totient is φ = 21730458.

The previous prime is 21730447. The next prime is 21730463. The reversal of 21730459 is 95403712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21730459 - 2¹¹ = 21728411 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21730459.

It is not a weakly prime, because it can be changed into another prime (21730439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10865229 + 10865230.

It is an arithmetic number, because the mean of its divisors is an integer number (10865230).

Almost surely, 2^21730459 is an apocalyptic number.

21730459 is a deficient number, since it is larger than the sum of its proper divisors (1).

21730459 is an equidigital number, since it uses as much as digits as its factorization.

21730459 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 21730459 is about 4661.5940406689. The cubic root of 21730459 is about 279.0548874341.

The spelling of 21730459 in words is "twenty-one million, seven hundred thirty thousand, four hundred fifty-nine".