191001820 has 12 divisors (see below), whose sum is σ = 401103864. Its totient is φ = 76400720.

The previous prime is 191001803. The next prime is 191001823. The reversal of 191001820 is 28100191.

It is a junction number, because it is equal to n+sod(n) for n = 191001791 and 191001800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191001823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4775026 + ... + 4775065.

It is an arithmetic number, because the mean of its divisors is an integer number (33425322).

Almost surely, 2^191001820 is an apocalyptic number.

191001820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

191001820 is an abundant number, since it is smaller than the sum of its proper divisors (210102044).

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

191001820 is a wasteful number, since it uses less digits than its factorization.

191001820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9550100 (or 9550098 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 22.

The square root of 191001820 is about 13820.3408062175. The cubic root of 191001820 is about 575.8983512436.

The spelling of 191001820 in words is "one hundred ninety-one million, one thousand, eight hundred twenty".