19959813 has 6 divisors (see below), whose sum is σ = 28830854. Its totient is φ = 13306536.

The previous prime is 19959809. The next prime is 19959817. The reversal of 19959813 is 31895991.

It is an interprime number because it is at equal distance from previous prime (19959809) and next prime (19959817).

It can be written as a sum of positive squares in only one way, i.e., 10614564 + 9345249 = 3258^2 + 3057^2 .

It is not a de Polignac number, because 19959813 - 2² = 19959809 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19959817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1108870 + ... + 1108887.

Almost surely, 2^19959813 is an apocalyptic number.

It is an amenable number.

19959813 is a deficient number, since it is larger than the sum of its proper divisors (8871041).

19959813 is a wasteful number, since it uses less digits than its factorization.

19959813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2217763 (or 2217760 counting only the distinct ones).

The product of its digits is 87480, while the sum is 45.

The square root of 19959813 is about 4467.6406525145. The cubic root of 19959813 is about 271.2598325840.

The spelling of 19959813 in words is "nineteen million, nine hundred fifty-nine thousand, eight hundred thirteen".