21999559 has 2 divisors, whose sum is σ = 21999560. Its totient is φ = 21999558.

The previous prime is 21999541. The next prime is 21999583. The reversal of 21999559 is 95599912.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21999559 - 2¹⁹ = 21475271 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21999539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10999779 + 10999780.

It is an arithmetic number, because the mean of its divisors is an integer number (10999780).

Almost surely, 2^21999559 is an apocalyptic number.

21999559 is a deficient number, since it is larger than the sum of its proper divisors (1).

21999559 is an equidigital number, since it uses as much as digits as its factorization.

21999559 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 328050, while the sum is 49.

The square root of 21999559 is about 4690.3687488299. The cubic root of 21999559 is about 280.2020607813.

The spelling of 21999559 in words is "twenty-one million, nine hundred ninety-nine thousand, five hundred fifty-nine".