21768583 has 2 divisors, whose sum is σ = 21768584. Its totient is φ = 21768582.

The previous prime is 21768569. The next prime is 21768587. The reversal of 21768583 is 38586712.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21768583 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21768587) 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, 10884291 + 10884292.

It is an arithmetic number, because the mean of its divisors is an integer number (10884292).

Almost surely, 2^21768583 is an apocalyptic number.

21768583 is a deficient number, since it is larger than the sum of its proper divisors (1).

21768583 is an equidigital number, since it uses as much as digits as its factorization.

21768583 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 80640, while the sum is 40.

The square root of 21768583 is about 4665.6814078975. The cubic root of 21768583 is about 279.2179837446.

The spelling of 21768583 in words is "twenty-one million, seven hundred sixty-eight thousand, five hundred eighty-three".