38643781 has 4 divisors (see below), whose sum is σ = 42156864. Its totient is φ = 35130700.

The previous prime is 38643779. The next prime is 38643793. The reversal of 38643781 is 18734683.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 38643781 - 2¹ = 38643779 is a prime.

It is a super-2 number, since 2×38643781² = 2986683619951922, 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 (38643181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1756525 + ... + 1756546.

It is an arithmetic number, because the mean of its divisors is an integer number (10539216).

Almost surely, 2^38643781 is an apocalyptic number.

It is an amenable number.

38643781 is a deficient number, since it is larger than the sum of its proper divisors (3513083).

38643781 is a wasteful number, since it uses less digits than its factorization.

38643781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3513082.

The product of its digits is 96768, while the sum is 40.

The square root of 38643781 is about 6216.4122289308. The cubic root of 38643781 is about 338.0854941698.

The spelling of 38643781 in words is "thirty-eight million, six hundred forty-three thousand, seven hundred eighty-one".