21108541 has 2 divisors, whose sum is σ = 21108542. Its totient is φ = 21108540.

The previous prime is 21108539. The next prime is 21108553. The reversal of 21108541 is 14580112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18028516 + 3080025 = 4246^2 + 1755^2 .

It is a cyclic number.

It is not a de Polignac number, because 21108541 - 2¹ = 21108539 is a prime.

Together with 21108539, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21102541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10554270 + 10554271.

It is an arithmetic number, because the mean of its divisors is an integer number (10554271).

Almost surely, 2^21108541 is an apocalyptic number.

It is an amenable number.

21108541 is a deficient number, since it is larger than the sum of its proper divisors (1).

21108541 is an equidigital number, since it uses as much as digits as its factorization.

21108541 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 320, while the sum is 22.

The square root of 21108541 is about 4594.4032256649. The cubic root of 21108541 is about 276.3669286541.

Adding to 21108541 its reverse (14580112), we get a palindrome (35688653).

The spelling of 21108541 in words is "twenty-one million, one hundred eight thousand, five hundred forty-one".