201819939861 has 8 divisors (see below), whose sum is σ = 269202075520. Its totient is φ = 134492215392.

The previous prime is 201819939821. The next prime is 201819939863. The reversal of 201819939861 is 168939918102.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 201819939861 - 2⁷ = 201819939733 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (201819939863) 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 7 ways as a sum of consecutive naturals, for example, 13594141 + ... + 13608978.

It is an arithmetic number, because the mean of its divisors is an integer number (33650259440).

Almost surely, 2^201819939861 is an apocalyptic number.

It is an amenable number.

201819939861 is a deficient number, since it is larger than the sum of its proper divisors (67382135659).

201819939861 is a wasteful number, since it uses less digits than its factorization.

201819939861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27205595.

The product of its (nonzero) digits is 1679616, while the sum is 57.

The spelling of 201819939861 in words is "two hundred one billion, eight hundred nineteen million, nine hundred thirty-nine thousand, eight hundred sixty-one".