221665400 has 96 divisors (see below), whose sum is σ = 591926400. Its totient is φ = 76348800.

The previous prime is 221665369. The next prime is 221665427. The reversal of 221665400 is 4566122.

221665400 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 221665400.

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, 39149 + ... + 44451.

It is an arithmetic number, because the mean of its divisors is an integer number (6165900).

Almost surely, 2^221665400 is an apocalyptic number.

221665400 is a gapful number since it is divisible by the number (20) 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 221665400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (295963200).

221665400 is an abundant number, since it is smaller than the sum of its proper divisors (370261000).

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

221665400 is a wasteful number, since it uses less digits than its factorization.

221665400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5349 (or 5340 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 221665400 is about 14888.4317508595. The cubic root of 221665400 is about 605.2005345749.

The spelling of 221665400 in words is "two hundred twenty-one million, six hundred sixty-five thousand, four hundred".