381647781 has 24 divisors (see below), whose sum is σ = 581080864. Its totient is φ = 250251120.

The previous prime is 381647771. The next prime is 381647821. The reversal of 381647781 is 187746183.

It is not a de Polignac number, because 381647781 - 2⁹ = 381647269 is a prime.

It is a super-2 number, since 2×381647781² = 291310057484447922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (381647741) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1950 + ... + 27696.

Almost surely, 2^381647781 is an apocalyptic number.

It is an amenable number.

381647781 is a deficient number, since it is larger than the sum of its proper divisors (199433083).

381647781 is an equidigital number, since it uses as much as digits as its factorization.

381647781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25823 (or 25811 counting only the distinct ones).

The product of its digits is 225792, while the sum is 45.

The square root of 381647781 is about 19535.8076618296. The cubic root of 381647781 is about 725.3610764231.

The spelling of 381647781 in words is "three hundred eighty-one million, six hundred forty-seven thousand, seven hundred eighty-one".