21409559 has 2 divisors, whose sum is σ = 21409560. Its totient is φ = 21409558.

The previous prime is 21409543. The next prime is 21409603. The reversal of 21409559 is 95590412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21409559 - 2⁴ = 21409543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21409529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10704779 + 10704780.

It is an arithmetic number, because the mean of its divisors is an integer number (10704780).

Almost surely, 2^21409559 is an apocalyptic number.

21409559 is a deficient number, since it is larger than the sum of its proper divisors (1).

21409559 is an equidigital number, since it uses as much as digits as its factorization.

21409559 is an evil number, because the sum of its binary digits is even.

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

The square root of 21409559 is about 4627.0464661596. The cubic root of 21409559 is about 277.6744416279.

The spelling of 21409559 in words is "twenty-one million, four hundred nine thousand, five hundred fifty-nine".