221215655544 has 96 divisors (see below), whose sum is σ = 600420833280. Its totient is φ = 67888159872.

The previous prime is 221215655449. The next prime is 221215655561. The reversal of 221215655544 is 445556512122.

It is a junction number, because it is equal to n+sod(n) for n = 221215655496 and 221215655505.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1482247 + ... + 1624649.

It is an arithmetic number, because the mean of its divisors is an integer number (6254383680).

Almost surely, 2^221215655544 is an apocalyptic number.

221215655544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221215655544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (300210416640).

221215655544 is an abundant number, since it is smaller than the sum of its proper divisors (379205177736).

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

221215655544 is a wasteful number, since it uses less digits than its factorization.

221215655544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142821 (or 142804 counting only the distinct ones).

The product of its digits is 480000, while the sum is 42.

The spelling of 221215655544 in words is "two hundred twenty-one billion, two hundred fifteen million, six hundred fifty-five thousand, five hundred forty-four".