2178221854691 has 8 divisors (see below), whose sum is σ = 2207485423104. Its totient is φ = 2149114359240.

The previous prime is 2178221854681. The next prime is 2178221854723. The reversal of 2178221854691 is 1964581228712.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2178221854691 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2178221854681) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38990141 + ... + 39045966.

It is an arithmetic number, because the mean of its divisors is an integer number (275935677888).

Almost surely, 2^{2178221854691} is an apocalyptic number.

2178221854691 is a deficient number, since it is larger than the sum of its proper divisors (29263568413).

2178221854691 is a wasteful number, since it uses less digits than its factorization.

2178221854691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78036481.

The product of its digits is 3870720, while the sum is 56.

The spelling of 2178221854691 in words is "two trillion, one hundred seventy-eight billion, two hundred twenty-one million, eight hundred fifty-four thousand, six hundred ninety-one".