21563449 has 2 divisors, whose sum is σ = 21563450. Its totient is φ = 21563448.

The previous prime is 21563419. The next prime is 21563453. The reversal of 21563449 is 94436512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19891600 + 1671849 = 4460^2 + 1293^2 .

It is a cyclic number.

It is not a de Polignac number, because 21563449 - 2¹¹ = 21561401 is a prime.

It is not a weakly prime, because it can be changed into another prime (21563419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10781724 + 10781725.

It is an arithmetic number, because the mean of its divisors is an integer number (10781725).

Almost surely, 2^21563449 is an apocalyptic number.

It is an amenable number.

21563449 is a deficient number, since it is larger than the sum of its proper divisors (1).

21563449 is an equidigital number, since it uses as much as digits as its factorization.

21563449 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 34.

The square root of 21563449 is about 4643.6460890124. The cubic root of 21563449 is about 278.3381536291.

The spelling of 21563449 in words is "twenty-one million, five hundred sixty-three thousand, four hundred forty-nine".