391381638 has 8 divisors (see below), whose sum is σ = 782763288. Its totient is φ = 130460544.

The previous prime is 391381631. The next prime is 391381649. The reversal of 391381638 is 836183193.

It is a sphenic number, since it is the product of 3 distinct primes.

391381638 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 391381638.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391381631) 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, 32615131 + ... + 32615142.

It is an arithmetic number, because the mean of its divisors is an integer number (97845411).

Almost surely, 2^391381638 is an apocalyptic number.

391381638 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

391381638 is a wasteful number, since it uses less digits than its factorization.

391381638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65230278.

The product of its digits is 93312, while the sum is 42.

The square root of 391381638 is about 19783.3677112872. The cubic root of 391381638 is about 731.4761136969.

The spelling of 391381638 in words is "three hundred ninety-one million, three hundred eighty-one thousand, six hundred thirty-eight".