21804449 has 2 divisors, whose sum is σ = 21804450. Its totient is φ = 21804448.

The previous prime is 21804361. The next prime is 21804467. The reversal of 21804449 is 94440812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21669025 + 135424 = 4655^2 + 368^2 .

It is a cyclic number.

It is not a de Polignac number, because 21804449 - 2²⁴ = 5027233 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21804479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10902224 + 10902225.

It is an arithmetic number, because the mean of its divisors is an integer number (10902225).

Almost surely, 2^21804449 is an apocalyptic number.

It is an amenable number.

21804449 is a deficient number, since it is larger than the sum of its proper divisors (1).

21804449 is an equidigital number, since it uses as much as digits as its factorization.

21804449 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 21804449 is about 4669.5234232200. The cubic root of 21804449 is about 279.3712464733.

The spelling of 21804449 in words is "twenty-one million, eight hundred four thousand, four hundred forty-nine".