21766543 has 2 divisors, whose sum is σ = 21766544. Its totient is φ = 21766542.

The previous prime is 21766513. The next prime is 21766553. The reversal of 21766543 is 34566712.

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-21766543 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21766499 and 21766508.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21766513) 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, 10883271 + 10883272.

It is an arithmetic number, because the mean of its divisors is an integer number (10883272).

Almost surely, 2^21766543 is an apocalyptic number.

21766543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21766543 is an equidigital number, since it uses as much as digits as its factorization.

21766543 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 34.

The square root of 21766543 is about 4665.4627851908. The cubic root of 21766543 is about 279.2092613505.

The spelling of 21766543 in words is "twenty-one million, seven hundred sixty-six thousand, five hundred forty-three".