21745441 has 2 divisors, whose sum is σ = 21745442. Its totient is φ = 21745440.

The previous prime is 21745433. The next prime is 21745469. The reversal of 21745441 is 14454712.

It is an a-pointer prime, because the next prime (21745469) can be obtained adding 21745441 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13905441 + 7840000 = 3729^2 + 2800^2 .

It is a cyclic number.

It is not a de Polignac number, because 21745441 - 2³ = 21745433 is a prime.

It is not a weakly prime, because it can be changed into another prime (21745421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10872720 + 10872721.

It is an arithmetic number, because the mean of its divisors is an integer number (10872721).

Almost surely, 2^21745441 is an apocalyptic number.

It is an amenable number.

21745441 is a deficient number, since it is larger than the sum of its proper divisors (1).

21745441 is an equidigital number, since it uses as much as digits as its factorization.

21745441 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4480, while the sum is 28.

The square root of 21745441 is about 4663.2007248241. The cubic root of 21745441 is about 279.1190038873.

The spelling of 21745441 in words is "twenty-one million, seven hundred forty-five thousand, four hundred forty-one".