21560789 has 2 divisors, whose sum is σ = 21560790. Its totient is φ = 21560788.

The previous prime is 21560767. The next prime is 21560809. The reversal of 21560789 is 98706512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21464689 + 96100 = 4633^2 + 310^2 .

It is a cyclic number.

It is not a de Polignac number, because 21560789 - 2²⁰ = 20512213 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21560719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10780394 + 10780395.

It is an arithmetic number, because the mean of its divisors is an integer number (10780395).

Almost surely, 2^21560789 is an apocalyptic number.

It is an amenable number.

21560789 is a deficient number, since it is larger than the sum of its proper divisors (1).

21560789 is an equidigital number, since it uses as much as digits as its factorization.

21560789 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 21560789 is about 4643.3596673099. The cubic root of 21560789 is about 278.3267081821.

The spelling of 21560789 in words is "twenty-one million, five hundred sixty thousand, seven hundred eighty-nine".