21568541 has 2 divisors, whose sum is σ = 21568542. Its totient is φ = 21568540.

The previous prime is 21568493. The next prime is 21568567. The reversal of 21568541 is 14586512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20839225 + 729316 = 4565^2 + 854^2 .

It is a cyclic number.

It is not a de Polignac number, because 21568541 - 2²² = 17374237 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21568498 and 21568507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21567541) 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, 10784270 + 10784271.

It is an arithmetic number, because the mean of its divisors is an integer number (10784271).

Almost surely, 2^21568541 is an apocalyptic number.

It is an amenable number.

21568541 is a deficient number, since it is larger than the sum of its proper divisors (1).

21568541 is an equidigital number, since it uses as much as digits as its factorization.

21568541 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9600, while the sum is 32.

The square root of 21568541 is about 4644.1943327126. The cubic root of 21568541 is about 278.3600608594.

The spelling of 21568541 in words is "twenty-one million, five hundred sixty-eight thousand, five hundred forty-one".