21580613 has 2 divisors, whose sum is σ = 21580614. Its totient is φ = 21580612.

The previous prime is 21580609. The next prime is 21580673. The reversal of 21580613 is 31608512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11607649 + 9972964 = 3407^2 + 3158^2 .

It is a cyclic number.

It is not a de Polignac number, because 21580613 - 2² = 21580609 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21580673) 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, 10790306 + 10790307.

It is an arithmetic number, because the mean of its divisors is an integer number (10790307).

Almost surely, 2^21580613 is an apocalyptic number.

It is an amenable number.

21580613 is a deficient number, since it is larger than the sum of its proper divisors (1).

21580613 is an equidigital number, since it uses as much as digits as its factorization.

21580613 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 21580613 is about 4645.4938381188. The cubic root of 21580613 is about 278.4119842589.

The spelling of 21580613 in words is "twenty-one million, five hundred eighty thousand, six hundred thirteen".