21547541 has 2 divisors, whose sum is σ = 21547542. Its totient is φ = 21547540.

The previous prime is 21547529. The next prime is 21547583. The reversal of 21547541 is 14574512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19802500 + 1745041 = 4450^2 + 1321^2 .

It is a cyclic number.

It is not a de Polignac number, because 21547541 - 2¹⁰ = 21546517 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21547741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10773770 + 10773771.

It is an arithmetic number, because the mean of its divisors is an integer number (10773771).

Almost surely, 2^21547541 is an apocalyptic number.

It is an amenable number.

21547541 is a deficient number, since it is larger than the sum of its proper divisors (1).

21547541 is an equidigital number, since it uses as much as digits as its factorization.

21547541 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5600, while the sum is 29.

The square root of 21547541 is about 4641.9328948187. The cubic root of 21547541 is about 278.2696906691.

The spelling of 21547541 in words is "twenty-one million, five hundred forty-seven thousand, five hundred forty-one".