19850813 has 4 divisors (see below), whose sum is σ = 19960668. Its totient is φ = 19740960.

The previous prime is 19850807. The next prime is 19850851. The reversal of 19850813 is 31805891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31805891 = 13 ⋅2446607.

It can be written as a sum of positive squares in 2 ways, for example, as 1643524 + 18207289 = 1282^2 + 4267^2 .

It is a cyclic number.

It is not a de Polignac number, because 19850813 - 2⁴ = 19850797 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 (19850893) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54656 + ... + 55017.

It is an arithmetic number, because the mean of its divisors is an integer number (4990167).

Almost surely, 2^19850813 is an apocalyptic number.

It is an amenable number.

19850813 is a deficient number, since it is larger than the sum of its proper divisors (109855).

19850813 is a wasteful number, since it uses less digits than its factorization.

19850813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109854.

The product of its (nonzero) digits is 8640, while the sum is 35.

The square root of 19850813 is about 4455.4251200082. The cubic root of 19850813 is about 270.7651501313.

The spelling of 19850813 in words is "nineteen million, eight hundred fifty thousand, eight hundred thirteen".