221538240 has 672 divisors, whose sum is σ = 1011838464. Its totient is φ = 44789760.

The previous prime is 221538227. The next prime is 221538253. The reversal of 221538240 is 42835122.

It is an interprime number because it is at equal distance from previous prime (221538227) and next prime (221538253).

It is a tau number, because it is divible by the number of its divisors (672).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a zygodrome in base 6.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 5987502 + ... + 5987538.

It is an arithmetic number, because the mean of its divisors is an integer number (1505712).

Almost surely, 2^221538240 is an apocalyptic number.

221538240 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 221538240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (505919232).

221538240 is an abundant number, since it is smaller than the sum of its proper divisors (790300224).

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

221538240 is a wasteful number, since it uses less digits than its factorization.

221538240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87 (or 65 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 221538240 is about 14884.1607086191. The cubic root of 221538240 is about 605.0847865144.

The spelling of 221538240 in words is "two hundred twenty-one million, five hundred thirty-eight thousand, two hundred forty".