391555880 has 16 divisors (see below), whose sum is σ = 881000820. Its totient is φ = 156622336.

The previous prime is 391555873. The next prime is 391555897. The reversal of 391555880 is 88555193.

It can be written as a sum of positive squares in 2 ways, for example, as 380172004 + 11383876 = 19498^2 + 3374^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4894409 + ... + 4894488.

Almost surely, 2^391555880 is an apocalyptic number.

It is an amenable number.

391555880 is an abundant number, since it is smaller than the sum of its proper divisors (489444940).

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

391555880 is a wasteful number, since it uses less digits than its factorization.

391555880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9788908 (or 9788904 counting only the distinct ones).

The product of its (nonzero) digits is 216000, while the sum is 44.

The square root of 391555880 is about 19787.7709709810. The cubic root of 391555880 is about 731.5846479588.

It can be divided in two parts, 3915 and 55880, that added together give a palindrome (59795).

The spelling of 391555880 in words is "three hundred ninety-one million, five hundred fifty-five thousand, eight hundred eighty".