381540781 has 4 divisors (see below), whose sum is σ = 391852732. Its totient is φ = 371228832.

The previous prime is 381540779. The next prime is 381540811. The reversal of 381540781 is 187045183.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 187045183 = 13 ⋅14388091.

It can be written as a sum of positive squares in 2 ways, for example, as 292068100 + 89472681 = 17090^2 + 9459^2 .

It is a cyclic number.

It is not a de Polignac number, because 381540781 - 2¹ = 381540779 is a prime.

It is a super-2 number, since 2×381540781² = 291146735132179922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 10311913 = 381540781 / (3 + 8 + 1 + 5 + 4 + 0 + 7 + 8 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 381540781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (381540701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5155920 + ... + 5155993.

It is an arithmetic number, because the mean of its divisors is an integer number (97963183).

Almost surely, 2^381540781 is an apocalyptic number.

It is an amenable number.

381540781 is a deficient number, since it is larger than the sum of its proper divisors (10311951).

381540781 is a wasteful number, since it uses less digits than its factorization.

381540781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10311950.

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 381540781 is about 19533.0689089042. The cubic root of 381540781 is about 725.2932818985.

The spelling of 381540781 in words is "three hundred eighty-one million, five hundred forty thousand, seven hundred eighty-one".