221728843854 has 384 divisors, whose sum is σ = 597542400000. Its totient is φ = 61579574784.

The previous prime is 221728843849. The next prime is 221728843859. The reversal of 221728843854 is 458348827122.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (221728843849) and next prime (221728843859).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 221728843854.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221728843859) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1488112972 + ... + 1488113120.

It is an arithmetic number, because the mean of its divisors is an integer number (1556100000).

Almost surely, 2^221728843854 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221728843854, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (298771200000).

221728843854 is an abundant number, since it is smaller than the sum of its proper divisors (375813556146).

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

221728843854 is a wasteful number, since it uses less digits than its factorization.

221728843854 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 379 (or 353 counting only the distinct ones).

The product of its digits is 6881280, while the sum is 54.

The spelling of 221728843854 in words is "two hundred twenty-one billion, seven hundred twenty-eight million, eight hundred forty-three thousand, eight hundred fifty-four".