21058621 has 2 divisors, whose sum is σ = 21058622. Its totient is φ = 21058620.

The previous prime is 21058619. The next prime is 21058633. The reversal of 21058621 is 12685012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21031396 + 27225 = 4586^2 + 165^2 .

It is a cyclic number.

It is not a de Polignac number, because 21058621 - 2¹ = 21058619 is a prime.

Together with 21058619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21058721) 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, 10529310 + 10529311.

It is an arithmetic number, because the mean of its divisors is an integer number (10529311).

Almost surely, 2^21058621 is an apocalyptic number.

It is an amenable number.

21058621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21058621 is an equidigital number, since it uses as much as digits as its factorization.

21058621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 21058621 is about 4588.9673130237. The cubic root of 21058621 is about 276.1488948409.

The spelling of 21058621 in words is "twenty-one million, fifty-eight thousand, six hundred twenty-one".