221655456 has 288 divisors, whose sum is σ = 740952576. Its totient is φ = 62208000.

The previous prime is 221655443. The next prime is 221655457. The reversal of 221655456 is 654556122.

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×221655456² = 98262282349135872, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 221655456.

It is not an unprimeable number, because it can be changed into a prime (221655457) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3633666 + ... + 3633726.

It is an arithmetic number, because the mean of its divisors is an integer number (2572752).

Almost surely, 2^221655456 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221655456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (370476288).

221655456 is an abundant number, since it is smaller than the sum of its proper divisors (519297120).

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

221655456 is a wasteful number, since it uses less digits than its factorization.

221655456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156 (or 145 counting only the distinct ones).

The product of its digits is 72000, while the sum is 36.

The square root of 221655456 is about 14888.0977965622. The cubic root of 221655456 is about 605.1914845922.

It can be divided in two parts, 221655 and 456, that added together give a triangular number (222111 = T₆₆₆).

The spelling of 221655456 in words is "two hundred twenty-one million, six hundred fifty-five thousand, four hundred fifty-six".