221505990 has 96 divisors (see below), whose sum is σ = 569159136. Its totient is φ = 55157760.

The previous prime is 221505989. The next prime is 221506049. The reversal of 221505990 is 99505122.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1223700 + ... + 1223880.

It is an arithmetic number, because the mean of its divisors is an integer number (5928741).

Almost surely, 2^221505990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221505990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (284579568).

221505990 is an abundant number, since it is smaller than the sum of its proper divisors (347653146).

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

221505990 is a wasteful number, since it uses less digits than its factorization.

221505990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 342 (or 323 counting only the distinct ones).

The product of its (nonzero) digits is 8100, while the sum is 33.

The square root of 221505990 is about 14883.0773027624. The cubic root of 221505990 is about 605.0554237411.

The spelling of 221505990 in words is "two hundred twenty-one million, five hundred five thousand, nine hundred ninety".