19810013 has 2 divisors, whose sum is σ = 19810014. Its totient is φ = 19810012.

The previous prime is 19810009. The next prime is 19810031. The reversal of 19810013 is 31001891.

Together with next prime (19810031) 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., 12264004 + 7546009 = 3502^2 + 2747^2 .

It is a cyclic number.

It is not a de Polignac number, because 19810013 - 2² = 19810009 is a prime.

It is a super-3 number, since 3×19810013³ (a number of 23 digits) contains 333 as substring.

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 (19810033) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9905006 + 9905007.

It is an arithmetic number, because the mean of its divisors is an integer number (9905007).

Almost surely, 2^19810013 is an apocalyptic number.

It is an amenable number.

19810013 is a deficient number, since it is larger than the sum of its proper divisors (1).

19810013 is an equidigital number, since it uses as much as digits as its factorization.

19810013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 23.

The square root of 19810013 is about 4450.8440772510. The cubic root of 19810013 is about 270.5795188535.

The spelling of 19810013 in words is "nineteen million, eight hundred ten thousand, thirteen".