21654559 has 2 divisors, whose sum is σ = 21654560. Its totient is φ = 21654558.

The previous prime is 21654541. The next prime is 21654599. The reversal of 21654559 is 95545612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21654559 - 2²¹ = 19557407 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21654599) 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, 10827279 + 10827280.

It is an arithmetic number, because the mean of its divisors is an integer number (10827280).

Almost surely, 2^21654559 is an apocalyptic number.

21654559 is a deficient number, since it is larger than the sum of its proper divisors (1).

21654559 is an equidigital number, since it uses as much as digits as its factorization.

21654559 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54000, while the sum is 37.

The square root of 21654559 is about 4653.4459274821. The cubic root of 21654559 is about 278.7296147627.

It can be divided in two parts, 2165 and 4559, that added together give a square (6724 = 82²).

The spelling of 21654559 in words is "twenty-one million, six hundred fifty-four thousand, five hundred fifty-nine".