211815671331821 has 12 divisors (see below), whose sum is σ = 227160148334112. Its totient is φ = 197130448495728.

The previous prime is 211815671331811. The next prime is 211815671331841. The reversal of 211815671331821 is 128133176518112.

It is a de Polignac number, because none of the positive numbers 2^k-211815671331821 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 211815671331821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211815671331811) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3363510155 + ... + 3363573128.

It is an arithmetic number, because the mean of its divisors is an integer number (18930012361176).

Almost surely, 2^{211815671331821} is an apocalyptic number.

It is an amenable number.

211815671331821 is a deficient number, since it is larger than the sum of its proper divisors (15344477002291).

211815671331821 is an equidigital number, since it uses as much as digits as its factorization.

211815671331821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6727083380 (or 6727083343 counting only the distinct ones).

The product of its digits is 483840, while the sum is 50.

The spelling of 211815671331821 in words is "two hundred eleven trillion, eight hundred fifteen billion, six hundred seventy-one million, three hundred thirty-one thousand, eight hundred twenty-one".