21031559 has 2 divisors, whose sum is σ = 21031560. Its totient is φ = 21031558.

The previous prime is 21031531. The next prime is 21031627. The reversal of 21031559 is 95513012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21031559 - 2⁸ = 21031303 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 (21031529) 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, 10515779 + 10515780.

It is an arithmetic number, because the mean of its divisors is an integer number (10515780).

Almost surely, 2^21031559 is an apocalyptic number.

21031559 is a deficient number, since it is larger than the sum of its proper divisors (1).

21031559 is an equidigital number, since it uses as much as digits as its factorization.

21031559 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1350, while the sum is 26.

The square root of 21031559 is about 4586.0177714440. The cubic root of 21031559 is about 276.0305530484.

The spelling of 21031559 in words is "twenty-one million, thirty-one thousand, five hundred fifty-nine".