38993781 has 4 divisors (see below), whose sum is σ = 51991712. Its totient is φ = 25995852.

The previous prime is 38993771. The next prime is 38993797. The reversal of 38993781 is 18739983.

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 38993781 - 2⁷ = 38993653 is a prime.

It is a super-2 number, since 2×38993781² = 3041029913351922, which contains 22 as substring.

It is the 6245-th Hogben number.

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 38993781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (38993741) by changing a digit.

It is a nontrivial repunit in base 6244.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6498961 + ... + 6498966.

It is an arithmetic number, because the mean of its divisors is an integer number (12997928).

Almost surely, 2^38993781 is an apocalyptic number.

It is an amenable number.

38993781 is a deficient number, since it is larger than the sum of its proper divisors (12997931).

38993781 is a wasteful number, since it uses less digits than its factorization.

38993781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12997930.

The product of its digits is 326592, while the sum is 48.

The square root of 38993781 is about 6244.5000600528. The cubic root of 38993781 is about 339.1031177501.

The spelling of 38993781 in words is "thirty-eight million, nine hundred ninety-three thousand, seven hundred eighty-one".