191001901820 has 24 divisors (see below), whose sum is σ = 401172676128. Its totient is φ = 76387678400.

The previous prime is 191001901819. The next prime is 191001901837. The reversal of 191001901820 is 28109100191.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 697496 + ... + 931935.

It is an arithmetic number, because the mean of its divisors is an integer number (16715528172).

Almost surely, 2^191001901820 is an apocalyptic number.

191001901820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

191001901820 is an abundant number, since it is smaller than the sum of its proper divisors (210170774308).

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

191001901820 is a wasteful number, since it uses less digits than its factorization.

191001901820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1635301 (or 1635299 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 32.

The spelling of 191001901820 in words is "one hundred ninety-one billion, one million, nine hundred one thousand, eight hundred twenty".