221555550 has 96 divisors (see below), whose sum is σ = 578534400. Its totient is φ = 56003200.

The previous prime is 221555549. The next prime is 221555557. The reversal of 221555550 is 55555122.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221555557) 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, 513835 + ... + 514265.

It is an arithmetic number, because the mean of its divisors is an integer number (6026400).

Almost surely, 2^221555550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221555550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (289267200).

221555550 is an abundant number, since it is smaller than the sum of its proper divisors (356978850).

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

221555550 is a wasteful number, since it uses less digits than its factorization.

221555550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 618 (or 613 counting only the distinct ones).

The product of its (nonzero) digits is 12500, while the sum is 30.

The square root of 221555550 is about 14884.7421878916. The cubic root of 221555550 is about 605.1005456370.

The spelling of 221555550 in words is "two hundred twenty-one million, five hundred fifty-five thousand, five hundred fifty".