21055589 has 2 divisors, whose sum is σ = 21055590. Its totient is φ = 21055588.

The previous prime is 21055583. The next prime is 21055607. The reversal of 21055589 is 98555012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19936225 + 1119364 = 4465^2 + 1058^2 .

It is a cyclic number.

It is not a de Polignac number, because 21055589 - 2¹² = 21051493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21055583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10527794 + 10527795.

It is an arithmetic number, because the mean of its divisors is an integer number (10527795).

Almost surely, 2^21055589 is an apocalyptic number.

It is an amenable number.

21055589 is a deficient number, since it is larger than the sum of its proper divisors (1).

21055589 is an equidigital number, since it uses as much as digits as its factorization.

21055589 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18000, while the sum is 35.

The square root of 21055589 is about 4588.6369435814. The cubic root of 21055589 is about 276.1356409874.

The spelling of 21055589 in words is "twenty-one million, fifty-five thousand, five hundred eighty-nine".