191591568820 has 48 divisors (see below), whose sum is σ = 423812108160. Its totient is φ = 72552737664.

The previous prime is 191591568787. The next prime is 191591568821. The reversal of 191591568820 is 28865195191.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191591568821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 375642 + ... + 724078.

It is an arithmetic number, because the mean of its divisors is an integer number (8829418920).

Almost surely, 2^191591568820 is an apocalyptic number.

191591568820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

191591568820 is an abundant number, since it is smaller than the sum of its proper divisors (232220539340).

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

191591568820 is a wasteful number, since it uses less digits than its factorization.

191591568820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 349912 (or 349910 counting only the distinct ones).

The product of its (nonzero) digits is 1555200, while the sum is 55.

The spelling of 191591568820 in words is "one hundred ninety-one billion, five hundred ninety-one million, five hundred sixty-eight thousand, eight hundred twenty".