21747541 has 2 divisors, whose sum is σ = 21747542. Its totient is φ = 21747540.

The previous prime is 21747529. The next prime is 21747563. The reversal of 21747541 is 14574712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17189316 + 4558225 = 4146^2 + 2135^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21747541 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21747841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10873770 + 10873771.

It is an arithmetic number, because the mean of its divisors is an integer number (10873771).

Almost surely, 2^21747541 is an apocalyptic number.

It is an amenable number.

21747541 is a deficient number, since it is larger than the sum of its proper divisors (1).

21747541 is an equidigital number, since it uses as much as digits as its factorization.

21747541 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7840, while the sum is 31.

The square root of 21747541 is about 4663.4258866203. The cubic root of 21747541 is about 279.1279886218.

The spelling of 21747541 in words is "twenty-one million, seven hundred forty-seven thousand, five hundred forty-one".