21361013 has 2 divisors, whose sum is σ = 21361014. Its totient is φ = 21361012.

The previous prime is 21361003. The next prime is 21361031. The reversal of 21361013 is 31016312.

Together with next prime (21361031) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18464209 + 2896804 = 4297^2 + 1702^2 .

It is a cyclic number.

It is not a de Polignac number, because 21361013 - 2¹² = 21356917 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21360982 and 21361000.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21361003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10680506 + 10680507.

It is an arithmetic number, because the mean of its divisors is an integer number (10680507).

Almost surely, 2^21361013 is an apocalyptic number.

It is an amenable number.

21361013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21361013 is an equidigital number, since it uses as much as digits as its factorization.

21361013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 21361013 is about 4621.7975940104. The cubic root of 21361013 is about 277.4644079558.

Adding to 21361013 its reverse (31016312), we get a palindrome (52377325).

The spelling of 21361013 in words is "twenty-one million, three hundred sixty-one thousand, thirteen".