21788933 has 2 divisors, whose sum is σ = 21788934. Its totient is φ = 21788932.

The previous prime is 21788927. The next prime is 21788959. The reversal of 21788933 is 33988712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19651489 + 2137444 = 4433^2 + 1462^2 .

It is a cyclic number.

It is not a de Polignac number, because 21788933 - 2⁸ = 21788677 is a prime.

It is a super-5 number, since 5×21788933⁵ (a number of 38 digits) contains 55555 as substring. Note that it is a super-d number also for d = 3.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21788903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10894466 + 10894467.

It is an arithmetic number, because the mean of its divisors is an integer number (10894467).

Almost surely, 2^21788933 is an apocalyptic number.

It is an amenable number.

21788933 is a deficient number, since it is larger than the sum of its proper divisors (1).

21788933 is an equidigital number, since it uses as much as digits as its factorization.

21788933 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 41.

The square root of 21788933 is about 4667.8617160323. The cubic root of 21788933 is about 279.3049640851.

It can be divided in two parts, 2178 and 8933, that added together give a palindrome (11111).

The spelling of 21788933 in words is "twenty-one million, seven hundred eighty-eight thousand, nine hundred thirty-three".