21559429 has 2 divisors, whose sum is σ = 21559430. Its totient is φ = 21559428.

The previous prime is 21559427. The next prime is 21559463. The reversal of 21559429 is 92495512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11937025 + 9622404 = 3455^2 + 3102^2 .

It is a cyclic number.

It is not a de Polignac number, because 21559429 - 2¹ = 21559427 is a prime.

Together with 21559427, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21559423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10779714 + 10779715.

It is an arithmetic number, because the mean of its divisors is an integer number (10779715).

Almost surely, 2^21559429 is an apocalyptic number.

It is an amenable number.

21559429 is a deficient number, since it is larger than the sum of its proper divisors (1).

21559429 is an equidigital number, since it uses as much as digits as its factorization.

21559429 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32400, while the sum is 37.

The square root of 21559429 is about 4643.2132193127. The cubic root of 21559429 is about 278.3208560110.

The spelling of 21559429 in words is "twenty-one million, five hundred fifty-nine thousand, four hundred twenty-nine".