391131648 has 120 divisors (see below), whose sum is σ = 1195473708. Its totient is φ = 122683392.

The previous prime is 391131623. The next prime is 391131667. The reversal of 391131648 is 846131193.

391131648 is a `hidden beast` number, since 3 + 9 + 1 + 1 + 3 + 1 + 648 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 389193984 + 1937664 = 19728^2 + 1392^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 75840 + ... + 80832.

Almost surely, 2^391131648 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 391131648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (597736854).

391131648 is an abundant number, since it is smaller than the sum of its proper divisors (804342060).

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

391131648 is a wasteful number, since it uses less digits than its factorization.

391131648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5034 (or 5015 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 391131648 is about 19777.0485158934. The cubic root of 391131648 is about 731.3203401984.

The spelling of 391131648 in words is "three hundred ninety-one million, one hundred thirty-one thousand, six hundred forty-eight".