191721856 has 64 divisors (see below), whose sum is σ = 415180800. Its totient is φ = 87851520.

The previous prime is 191721839. The next prime is 191721899. The reversal of 191721856 is 658127191.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is an unprimeable number.

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, 74121 + ... + 76663.

It is an arithmetic number, because the mean of its divisors is an integer number (6487200).

Almost surely, 2^191721856 is an apocalyptic number.

191721856 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 191721856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (207590400).

191721856 is an abundant number, since it is smaller than the sum of its proper divisors (223458944).

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

191721856 is a wasteful number, since it uses less digits than its factorization.

191721856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2607 (or 2595 counting only the distinct ones).

The product of its digits is 30240, while the sum is 40.

The square root of 191721856 is about 13846.3661658935. The cubic root of 191721856 is about 576.6211149751.

The spelling of 191721856 in words is "one hundred ninety-one million, seven hundred twenty-one thousand, eight hundred fifty-six".