391291540 has 24 divisors (see below), whose sum is σ = 835642080. Its totient is φ = 153863328.

The previous prime is 391291531. The next prime is 391291543. The reversal of 391291540 is 45192193.

It is a junction number, because it is equal to n+sod(n) for n = 391291496 and 391291505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391291543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 164622 + ... + 166981.

It is an arithmetic number, because the mean of its divisors is an integer number (34818420).

Almost surely, 2^391291540 is an apocalyptic number.

It is an amenable number.

391291540 is an abundant number, since it is smaller than the sum of its proper divisors (444350540).

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

391291540 is a wasteful number, since it uses less digits than its factorization.

391291540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331671 (or 331669 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 391291540 is about 19781.0904653914. The cubic root of 391291540 is about 731.4199795758.

The spelling of 391291540 in words is "three hundred ninety-one million, two hundred ninety-one thousand, five hundred forty".