381806813 has 4 divisors (see below), whose sum is σ = 381849468. Its totient is φ = 381764160.

The previous prime is 381806809. The next prime is 381806827. The reversal of 381806813 is 318608183.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 318608183 = 773 ⋅412171.

It can be written as a sum of positive squares in 2 ways, for example, as 332624644 + 49182169 = 18238^2 + 7013^2 .

It is a cyclic number.

It is not a de Polignac number, because 381806813 - 2² = 381806809 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 (381806713) 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, 2156 + ... + 27717.

It is an arithmetic number, because the mean of its divisors is an integer number (95462367).

Almost surely, 2^381806813 is an apocalyptic number.

It is an amenable number.

381806813 is a deficient number, since it is larger than the sum of its proper divisors (42655).

381806813 is a wasteful number, since it uses less digits than its factorization.

381806813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42654.

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 381806813 is about 19539.8775072926. The cubic root of 381806813 is about 725.4618146861.

The spelling of 381806813 in words is "three hundred eighty-one million, eight hundred six thousand, eight hundred thirteen".