391881616 has 75 divisors (see below), whose sum is σ = 894619793. Its totient is φ = 166286400.

The previous prime is 391881601. The next prime is 391881617. The reversal of 391881616 is 616188193.

It is a happy number.

The square root of 391881616 is 19796.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 376515216 + 15366400 = 19404^2 + 3920^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391881617) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 3879966 + ... + 3880066.

Almost surely, 2^391881616 is an apocalyptic number.

391881616 is the 19796-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 391881616

391881616 is an abundant number, since it is smaller than the sum of its proper divisors (502738177).

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

391881616 is an frugal number, since it uses more digits than its factorization.

391881616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238 (or 110 counting only the distinct ones).

The product of its digits is 62208, while the sum is 43.

The cubic root of 391881616 is about 731.7874605652.

It can be divided in two parts, 39188 and 1616, that added together give a palindrome (40804).

The spelling of 391881616 in words is "three hundred ninety-one million, eight hundred eighty-one thousand, six hundred sixteen".