21788719 has 2 divisors, whose sum is σ = 21788720. Its totient is φ = 21788718.

The previous prime is 21788681. The next prime is 21788729. The reversal of 21788719 is 91788712.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21788719 is a prime.

It is a super-3 number, since 3×21788719³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21788729) 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, 10894359 + 10894360.

It is an arithmetic number, because the mean of its divisors is an integer number (10894360).

Almost surely, 2^21788719 is an apocalyptic number.

21788719 is a deficient number, since it is larger than the sum of its proper divisors (1).

21788719 is an equidigital number, since it uses as much as digits as its factorization.

21788719 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 56448, while the sum is 43.

The square root of 21788719 is about 4667.8387932747. The cubic root of 21788719 is about 279.3040496842.

The spelling of 21788719 in words is "twenty-one million, seven hundred eighty-eight thousand, seven hundred nineteen".