381815257 has 4 divisors (see below), whose sum is σ = 404274996. Its totient is φ = 359355520.

The previous prime is 381815237. The next prime is 381815267. The reversal of 381815257 is 752518183.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 752518183 = 223 ⋅3374521.

It can be written as a sum of positive squares in 2 ways, for example, as 357815056 + 24000201 = 18916^2 + 4899^2 .

It is not a de Polignac number, because 381815257 - 2¹¹ = 381813209 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (381815207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11229844 + ... + 11229877.

It is an arithmetic number, because the mean of its divisors is an integer number (101068749).

Almost surely, 2^381815257 is an apocalyptic number.

It is an amenable number.

381815257 is a deficient number, since it is larger than the sum of its proper divisors (22459739).

381815257 is a wasteful number, since it uses less digits than its factorization.

381815257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22459738.

The product of its digits is 67200, while the sum is 40.

The square root of 381815257 is about 19540.0935770533. The cubic root of 381815257 is about 725.4671627262.

The spelling of 381815257 in words is "three hundred eighty-one million, eight hundred fifteen thousand, two hundred fifty-seven".