21219589 has 2 divisors, whose sum is σ = 21219590. Its totient is φ = 21219588.

The previous prime is 21219581. The next prime is 21219631. The reversal of 21219589 is 98591212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18792225 + 2427364 = 4335^2 + 1558^2 .

It is a cyclic number.

It is not a de Polignac number, because 21219589 - 2³ = 21219581 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21219581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10609794 + 10609795.

It is an arithmetic number, because the mean of its divisors is an integer number (10609795).

Almost surely, 2^21219589 is an apocalyptic number.

It is an amenable number.

21219589 is a deficient number, since it is larger than the sum of its proper divisors (1).

21219589 is an equidigital number, since it uses as much as digits as its factorization.

21219589 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 37.

The square root of 21219589 is about 4606.4725115863. The cubic root of 21219589 is about 276.8507191313.

The spelling of 21219589 in words is "twenty-one million, two hundred nineteen thousand, five hundred eighty-nine".