221221440 has 168 divisors, whose sum is σ = 830202048. Its totient is φ = 53621760.

The previous prime is 221221423. The next prime is 221221447. The reversal of 221221440 is 44122122.

221221440 is a `hidden beast` number, since 2 + 2 + 1 + 221 + 440 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (221221447) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28189 + ... + 35171.

Almost surely, 2^221221440 is an apocalyptic number.

221221440 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 221221440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (415101024).

221221440 is an abundant number, since it is smaller than the sum of its proper divisors (608980608).

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

221221440 is a wasteful number, since it uses less digits than its factorization.

221221440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7017 (or 7004 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 221221440 is about 14873.5147157624. The cubic root of 221221440 is about 604.7962248862.

Adding to 221221440 its reverse (44122122), we get a palindrome (265343562).

The spelling of 221221440 in words is "two hundred twenty-one million, two hundred twenty-one thousand, four hundred forty".