21904559 has 2 divisors, whose sum is σ = 21904560. Its totient is φ = 21904558.

The previous prime is 21904523. The next prime is 21904583. The reversal of 21904559 is 95540912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21904559 - 2¹⁶ = 21839023 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21904159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10952279 + 10952280.

It is an arithmetic number, because the mean of its divisors is an integer number (10952280).

Almost surely, 2^21904559 is an apocalyptic number.

21904559 is a deficient number, since it is larger than the sum of its proper divisors (1).

21904559 is an equidigital number, since it uses as much as digits as its factorization.

21904559 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16200, while the sum is 35.

The square root of 21904559 is about 4680.2306567091. The cubic root of 21904559 is about 279.7981495902.

The spelling of 21904559 in words is "twenty-one million, nine hundred four thousand, five hundred fifty-nine".