21916513 has 2 divisors, whose sum is σ = 21916514. Its totient is φ = 21916512.

The previous prime is 21916511. The next prime is 21916529. The reversal of 21916513 is 31561912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12723489 + 9193024 = 3567^2 + 3032^2 .

It is a cyclic number.

It is not a de Polignac number, because 21916513 - 2¹ = 21916511 is a prime.

Together with 21916511, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21916511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10958256 + 10958257.

It is an arithmetic number, because the mean of its divisors is an integer number (10958257).

Almost surely, 2^21916513 is an apocalyptic number.

It is an amenable number.

21916513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21916513 is an equidigital number, since it uses as much as digits as its factorization.

21916513 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1620, while the sum is 28.

The square root of 21916513 is about 4681.5075563327. The cubic root of 21916513 is about 279.8490385220.

The spelling of 21916513 in words is "twenty-one million, nine hundred sixteen thousand, five hundred thirteen".